@benjamingeer @AmenZwaamen zwa, esq. @dougmerrittDougMerritt (log😅 = 💧log😄) @benjamingeer @brettm💙🩷💜Ⓑⓡⓔⓣⓣ🐡🍉🐧 @SeaJay I think there are probably a lot of conditions that determine whether hashtags are useful:
1. There is one or a few obvious hashtags that you would use for a given topic.
2. It won't collide with other unrelated words that are written the same way (in a language widely used on the platform).
3. There is an obvious hashtag that's sufficiently specific to target a specific audience (rather than being a mix of very different things).
4. There is not too much spamming of the hashtag with low quality content (from bots or people habitually using the hashtag on large numbers of posts).
5. There is a critical mass of users who use the hashtag within a given time interval (either it's just a popular topic on the platform, the platform is so large that the long tail effect is in operation, or it's related to some specific event that happens in a short period of time with heightened interest).

For example, I think things like programming languages work on Fedi because they have an agreed upon name, it's often not something that people would be likely to hashtag with a different meaning, it's not overly broad, and Fedi is full of coders.

I think I've tried to use them on topics that don't meet some or all of those criteria, like questions about Apple software (where there is plenty of interest in the topic, but it's broad and gets some amount of spam) or physics (where there's a much smaller set of users who are interested, and it's a broad topic where people can be interested in very different things, both in terms of sub-fields and level of sophistication).