As annoying as they can be, some sort of implementation of hashtags can be useful. For example, if I'm attempting to find a study on o/STEM on puberty blockers, this can act as another way to pull up related posts assuming the OP tagged it as such.

Tumblr also ran with a really creative use of the hashtag system when developers observed individuals talking in the hashtags to each other as a means of adding more quiet thoughts and commentary without wanting to detract from the original post. I'm not suggesting this to be implemented here (it makes less sense here for that imo), but I am raising this as just a creative example of a hashtag system being used beyond the means of just filtering content and adding to user communication. More features that add to communication and filtering in small ways allows for a culture to be created out of such features in surprising ways, in which a greater system can then be built and shape platforms uniquely.

It's also, and this is just a thought, something that might be useful to gage user interest in a topic if there was a way to track how often users assigned a specific hashtag to something (1.2k #asphalt), which may be visible to just you as admins or visible to users as a whole. It can be a feature within circles (i.e., searching "#possum" in o/whatever only pulls up posts with this tag from o/whatever), or it can be used as a general site tool (#possum would pull up whatever is tagged as #possum across the site). The search bar does a lot of this already, but I'm just voicing ideas.

Hashtags might be a more appropriate suggestion for later rather than sooner to prioritize other things and allow the site to evolve, or they might not be relevant to how this platform is designed, but I wanted to leave that idea here nonetheless.

Edit: Perhaps hash tags are sort of similar to flairs? So maybe the flair feature can be more refined, or replaced, or whatever.