Well there are some different ideas for implementing hashtags. One idea was that Lemmy could follow hashtags from Mastodon etc to display them in the corresponding community. The only way to receive these hashtag posts is by following the users who create them, but Lemmy doesnt support user following.
Another option would be that Lemmy adds hashtags to posts so that they are picked up by Mastodon etc, without Lemmy itself using hashtags. This is definitely doable, for example it would be very easy to automatically add hashtags based on the community name, so everything in /c/memes would have #memes hashtag. It would also be possible to configure the hashtags in community settings similar to this tagginator tool, but that would require more extensive changes.
A third option would be to add hashtags based on post tags, thats what db0 was discussing before and which I referenced with that comment. However we are still discussing how post tags should work as you can see from the issue and from the RFC.
So option two or three seem reasonable, but like you say none of the maintainers seem to give this much priority. So the only way this will get implemented is if someone else writes the code. Thats just the reality, complaining wont change anything.