@adnan What this particular user wrote or did isn't as bad as it could be, either. But the idea of anyone being able to stalk a hashtag via the biggest, most open instance and then potentially direct a mob towards it presents a serious potential abuse vector for the #Fediverse.
I like hashtags. I like that it's possible to view them publicly. But having seen this situation it makes me think there need to be options for people to use them with posts that are only visible within the ecosystem.