The outlined issues don't seem to be lemmy exclusive, but then again, I've spent quite a short time here.
The toxicity is caused by the society, not by the platform. From my experience, one can always find a more toxic subreddit.
Reddit is just as much moderated by volunteers, that's the reason I started using reddit. Also, having corporate admins doesn't make the platform any more spam resistant.
If anything I would expect these problems to be more prevalent in smaller (lemmy) platforms and stabilize with growth to reddits level.
Now I'm not trying to defend lemmy, but being even more community driven I want it to succeed and become what reddit used to be.