someone inevitably shuts down any curiosity by suggesting that it's a political echo-chamber
I've said it before, and I'll say it again: I think .ml acting as the official or at least de-facto "flagship" instance is doing more harm than good. I've seen the same arguments you mentioned, and it always seems to go back to either of the two .ml instances or Hexbear. When political ideology is forced into every interaction, it always seemed it was coming from one of those three.
I've shown people Lemmy World as an example that it's not all political circlejerks, but I don't know how many of them stuck with it.