I don’t think it’s a Mastodon problem. It’s a generalist social network problem. Facebook, Twitter, Mastodon, why are we using those? For some, it’s “to keep in touch” with friends and family, and they’re happy seeing any activity, preferably things that makes them smile (that’s more Facebook). For others, it’s a mean to build street cred in their industry by publicly saying on topic things that sound smart (that was Twitter). But if you look for interesting discussions on things you like, in order to learn something, they’re terrible at that. It’s where specialized communities, discussing only one topic, shine. It used to be forums, then reddit, now lemmy. RSS is also a very good way to get that kick.