The users, communities and posts of those instances are enabled and pushed to innocent users as well and not just contained on their own “island”.
In their own blogs they actually offer the solution to be defederation of harmful instances but nothing is currently happening with the situation.
.ml is large yes and has some general purpose communities.
Although, quite clearly and easily confirmable by anyone, it hosts the problematic issues and the related user base described in this thread.
The whole ethos as described in the blog history of lemmy suggests to let those kinds of instances be on their own. Not wreck the wreckers.