Currently users you block can still see your posts, reply to those posts, and trigger notifications when they do reply.
You can read the beginning of messages people you have blocked in your notifications tab, but have to unblock users to see the rest of what everyone else reading the replies to your post can see.
A “blocking” feature that is only inconvenient to the blocker is worse than no blocking feature at all, equivalent to trying to escape a fistfight by turning invisible but actually just closing your eyes.
This goes both ways, and it’s one of the biggest problems with your proposal - if you pre-emptively block anyone who might disagree with you, any third party will only ever hear your side and will be denied the opportunity to see your ideas challenged.