It is extremely heavily moderated in favor of communism, so it is a very big echo chamber. Everything seems very calm and respectable as long as you don’t dig too deep, because any dissenting opinions quickly get removed. So there isn’t a whole lot of argument that happens among .ml users. But checking the mod logs tells a very different story.

Also, it’s the only instance that the lead Lemmy dev uses, so anyone who wants to stay up to date on lemmy’s development is forced to federate with .ml. There have also been some controversies about the dev putting dev donations towards running the instance, which ruffled a lot of feathers from people who want to support the dev but not the instance.