If I recall, it’s on the roadmap for lemmy development.

I’m glad exploding-heads is defederated, but my blocklist is quickly filling up with lemmygrad and I’d love to stop playing whack-a-mole on All

Which instances are filled with that filth? I’ve not seen any of the such…

Get used to it, it’ll do you good.
But yeah on kbin you can block instances.