That may all be true and all, but other services aren’t one guy.
It would be like signing up for a fediverse instance, which uses closed source software, and it’s just one guy running the service for a small amount of people.
I don’t know who runs Lemmy.world, but at no point do I think the admins are targeting me, to read through my inbox. My judgement says that’s not what the admins are doing with their time.
But this myspace clone had 300ish registered members on a single centralized closed source platform being run and created by one guy with zero oversight. I can’t say that he created the service specifically to spy on people, but it certainly doesn’t pass the sniff test.