When mike@flipboard.social interviewed @chrismessina on the Dot Social podcast;
https://dot-social.simplecast.com/episodes/chris-messina-nhUtOY8h
... they briefly criticised "hashtag stuffing". OK, guilty as charged.
But on the fediverse, hashtags are what we use for discovery instead of serendipity generators ("The Algorithms"). Along with community timelines, and now keyword searches, they are ways to browse the pool of posts your server has from everyone someone follows.