I feel like fundamentally these mathematical proofs miss the point of what people who don't like mill or view mill as damaging are trying to say.

The act of milling a card reveals the next card you would have drawn, and then makes it so you don't draw it.

So, first, consider the explicit effects of milling:

When the revealed card is a card you don't want or don't care about, this has a very low registered impact.

When the revealed card is a card that you did want or even more so a card that would have won you the game, this has a very high registered impact.

But mill also has an implicit effect: it gets you closer to cards below the milled card, obviously. Removing the top card from the deck doesn't magically make the deck have no top card, it just moves you down through the deck.

The problem with this is that players aren't psychic and don't have an exact end point in mind when they start a game. Nobody sits down to their game of magic and says "I will draw exactly 14 cards this game, so any card below the 14th doesn't matter". They also don't think "I will draw every card in my deck, every game".

This has a weird set of psychological implications for the group of people who don't like mill, specifically. It results in a situation where they can say to themselves that if the card they wanted was 'revealed' by mill, they would have been able to stall/extend the game that long anyway, so mill didn't "help them". Whereas, when a card they want is milled, they can point to the direct harm.

Fundamentally players who don't like mill are usually not misunderstanding something mathematical, although they might struggle to explain in non-mathematical terms, or might not have a good grasp on math. The actual problem is one of impact bias - they sharply feel the downsides of mill because the downsides are obvious and very clear, while the benefits are hidden and can be dismissed or explained away.