I think the issue we'd run into is that mill itself isn't a degenerate *mechanic*, it's a degenerate *deck archetype*, and that get a lot harder to ban. Because mill players are the worst kind of players - most of them are straight up griefers who don't even care if their decks can win or not (because while they're unfortunately strong in the current meta, in most metas, they *haven't* been particularly competitive), what they enjoy are the fact that mill decks upset opponents - but the mill mechanic itself is useful when played in a reasonable way. So the question is how to deal with the people who are running mill decks that nobody wants to play against and ruining the game for the 95% of people who actually want to play with the cards they've spent good money on, without ruining a perfectly serviceable mechanic for the people who just want an occasional trick up their sleeve for when their opponent who is leading the commander game just scryed 2, top-decked them both, and has an evil look on their face.
I think the issue we'd run into is that mill itself isn't a degenerate *mechanic*, it's a degenerate *deck archetype*, and that get a lot harder to ban. Because mill players are the worst kind of players - most of them are straight up griefers who don't even care if their decks can win or not (because while they're unfortunately strong in the current meta, in most metas, they *haven't* been particularly competitive), what they enjoy are the fact that mill decks upset opponents - but the mill mechanic itself is useful when played in a reasonable way. So the question is how to deal with the people who are running mill decks that nobody wants to play against and ruining the game for the 95% of people who actually want to play with the cards they've spent good money on, without ruining a perfectly serviceable mechanic for the people who just want an occasional trick up their sleeve for when their opponent who is leading the commander game just scryed 2, top-decked them both, and has an evil look on their face.