It really comes down to feature removal. Elon annihilated Twitter’s staff, and the more features they can cut, the less staff they need. It may not seem like much to maintain a block feature, and if you have a staff, it’s not. But you do need to have probably some sort of blocker backend service, a blocking UI, probably an unblocking UI (I dunno if that’s a thing I don’t use twitter), storage that keeps track of who blocked who, and somebody who knows how all that works.