Agreed. But I think what you're missing here is the culture of the theatre world. There's been a real push to racebend and genderbend theatre roles in the last few years, with the reasoning being that theatre is just a more creatively free environment. Audiences are inherently more willing to suspend disbelief at a live performance, the thinking goes, and as long as the actor can act / sing their chops off, that's all that matters. So you'll get things like a female Hamlet or a racially-diverse array of American founding fathers, and at the moment, nobody bats an eye at this. And if you're unsure about it, you're the one being controversial.
This is the argument the other side will end up reverting to, when "Dylan is just as much of a woman as you!" fails to work for them. Then it'll be "well, it's theatre anyway, and in theatre -" 🙄
The reason people are bringing up Dylan Mulvaney's awful hammy acting, and total inability to sing this part the way it should be sung, is to make the point that even by the standards of the racebent, genderbent, anything-goes world of the theatre, this casting is pure shit. There really is no excuse for it.