Users are moving to BlueSky, among other reasons, because "Block" means BLOCK. Once one user blocks another, there can be no further interaction between the two users unless the first user removes that block. Contrast this to the former Twitter, where a recent policy change allows blocked users to continue to view the blocking user's posts and comments, arguably creating a vehicle for cyberstalking...or worse.
In combination with a distinct lack of advertising, no algorithms that promote or demote individual posts, and the ability to read followed accounts' posts in reverse chronological order instead of scattered across the timeline by the previously-mentioned algorithms, the attractiveness of BlueSky becomes more apparent. In short, it's what Twitter was in the beginning, but with better guardrails.