The problem with mill

I'll try to summarize the entirety of problems people have with this deck in a simple short sentence: mill has no counter tech.

An overwhelming majority of decks in this game has some kind of counter compressed into one tech card: you can break destroy with armor, any ongoing deck with enchantress, discard with mobius etc. Mill has none. "Ooooh but I'm a smart little boy and I know that Arishem and Galactus counter mill". Great. Those are not tech cards, but build-around centerpieces and don't belong in this discussion.

So yes, the closest thing to counter mill if you don't want to tailor your deck around it is Cosmo I believe, but it is way too unreliable. So yes, until SD introduce a definitive counter to this kind of decks (or nerf them to the ground), people will continue to complain about mill. Especially when it gets more and more new cards to play with.