I cut Eternal Witness from my main cube and it feels profound. Witness has been a cube mainstay for as long as I have been cubing. It was the best creature in cube from the start and stayed that way for a long time. It wasn't really until we got things like Clique, Glen Elandra, Bloodbraid and Finks some years down the line that Witness started to have any real competition for the top slot in cube. You had things like Mother of Runes, Psychatog, Birds of Paradise, and Goblin Welder but these all had issues. Birds was great but mana dorks were not in short supply back then, it was things to do with the mana. Welder was and is a bomb but it is narrow and needs you to have things to support it. Psychatog was also pretty narrow and was not all that in the early game. It was just a finisher and might as well have been Morphling or Rainbow Efreet! Mother of Runes was a bit annoying but when all you are protecting is a Savannah Lions it is rather diminished. Witness was the top creature in cube for a good five years and then in the top ten for at least another five. Just three years ago I put Witness seventh on a top ten list for green dorks on that kind. It has slowly been losing potency since it was first printed but that rate of loss has significantly increased in the last three years.
I remember seeing Witness on the spoilers. This was so long ago that I was using the universities internet as my accommodation nor phone had access to such things. It makes it sound like Dickensian times and we didn't have the likes electricity... It was when spoilers frequently got things wrong, big things like casting cost. I was pretty confidant that Witness was such a card when I read it on the spoiler (as a .txt file none the less) as it was clearly far too good. I still recall the surprise I felt when I saw the first real one and found the spoiler to have been accurate.
Understanding why Witness was so good and how it has reached the point of no longer being very impressive does a good job of showing the change in the game over this near two decade period. She was one of very few tempo cards that provided card advantage. She would pull you ahead on the two main metrics of the game at the same time. Few other cards did this so effectively or universally. There were things like Phyrexian Rager and Solemn Simulacrum but they were rather less impressive. Describing a three mana 2/1 as a tempo card sounds laughable these days. That is only just a tempo play on turn one now. A 2/1 dies to everything and offers little threat. Back then doing anything at all represented tempo. You now had a threat that needed answering else you were going to win. Eternal Witness has legitimately done thousands of face damage in games with my cube. When you are the only creature in play for a significant number of turns it is pretty easy to go to town on a life total. There were not many good dorks nor were there things just cluttering up the board with token dorks leaving Witness pretty free to do useful work. Every deck would play Witness, aggro, combo, control, midrange, the works. It was always good. I have seen people play it for free on turn one with Black Lotus a fair number of times and often to good results! I recall in particular one notorious player always drafting some blue green deck with Witness as his only real win condition, usually finding some way to loop it with Time Walk effects. Often using Oath of Druids just to find the Witness!
There was then the issue of redundancy back then. Most magic cards were bad and there were not that many options on alternatives. If you wanted to kill a creature Swords to Plowshares was a thing. Terror or some Edict or Nekrataal were options. Vindicate and Terminate if you felt fancy. Beyond that it got very thin very fast. Decks very much tended towards being collections of random high powered cards. In certain matchups it would all become about a few key cards and so being able to use one of those cards multiple times thanks to Regrowth effects was huge. Cards these days are so broad in application and we have vast redundancy on common effects that the value of reusing something is greatly diminished. If you value a 2/1 at one mana then you are paying 2 mana for the Regrowth still and that is a huge tempo loss. No (unpowered) cube card stays good when you add two mana to the cost, there are multiple alternatives that become better. Why Witness back a Lightning Bolt when you can just Searing Spear as a simple example of this. GGR1 for 3 damage and a 2/1 sounds a lot worse than 1R for just the three damage thanks. Demonic Tutor is pretty poor in non-combo cubes these days for that same extra cost reason and Tutor was always and still is wildly better than Regrowth as you can play it early with no loss of functionality.
Planeswalkers have also changed much about the game, they make it important to have the tempo at any given point and do a lot of the heavy lifting when it comes to value generation. This has the effect of making the now low tempo play of Witness (thanks to creature power creep) more of a liability while rendering the value side of Witness less desirable. The real killer for Witness in the current state of cube is that you often cannot usefully play it on curve. If you do you are probably getting back a land or some random cheap cantrip card. This is fine but it isn't exactly getting back key cards. When you can't just toss down your three drop on curve and have it be useful it is pretty damning. Missing out on curving is very bad and so a low cost card that can be effectively dead early is a bad include. If you were just getting a land with your Witness then Nissa Vastwood Seer and Jadelight Ranger are substantially better options. They always work on curve and have further potential upside beyond a 2/1 and a land. Hell, Civic Wayfinder is better than Witness in cube most of the time these days.
Llanowar Visionary and Bala Ged Recovery have been the two final nails in the coffin for Witness. Recovery gives you all the perks of a Regrowth late when they are actually good without any of the drawbacks of a cruddy 2/1 body or being useless early on. Visionary on the other hand showcases a pretty perfect early cube curve play. Visionary is always a good play. The card Visionary gets you is better than what Witness will do in the all important early game and the body that comes with it is both more powerful and more useful.
So, Witness no longer cuts it and for several reasons. Creatures have become way more powerful and way more abundant. Tempo has become significantly more important. Redundancy has also increased significantly. And creatures that provide a two for one are common place. It feels surreal cutting a card that was one the pinnacle of what a creature could be. It is as if Ancestral Recall was no longer good enough card draw! I likely overlooked it for cutting for far longer that I should have simply down to how unimaginable it is cutting a card once so mighty. Witness may not be the first card that was once best in slot to get cut (Baneslayer Angel is a good example of this) but it is more that just that. Witness has been there since the very start of my cube experience. Almost all the other cards that were in cube back then are either still staples and bombs or were cut long ago. I am sad to see the little shaman go. I used to wish she was an elf, now I just wish she was a little better. Time for a reprint but with three modes to chose from in line with Knight of Autumn or Callous Bloodmage. So long and thanks for all the Regrowths.