@welshpixie is an admin who deals with sexist mastoadmins publicly. As she says, you don't _need_ a reason to block anyone.
As @aral has written before. You cannot talk to all 9bn people on earth in one lifetime. Block the rude and annoying ones.
There are some housebroken FOSS types who don't live in a well actually, putting a note on their profile reminds me why I blocked them and should they show up in a thread again? Always well-deserved.
Prune for your own sanity.