You see all the comments your server has noticed.
I've tried to go through why this happens in the article linked to in the original post, and at https://fedi.tips/which-posts-and-accounts-can-i-see-from-my-server/
The alternative to this system would be centralisation, but centralised services tend to end up being sold to Musk etc, invade privacy etc etc.
The idea of this place is to provide community-owned alternatves that can't be sold, don't trap you on one server, and don't invade privacy.