The active sort should help a little with this, but ya its definitely a problem. Besides just blocking meme-specific communities, can anyone think of ways we could make discussions more prominent for people who'd rather use lemmy for that?
You can't go wrong with taking inspiration from RES.
Having a filter for the type of posts next to the sort type would be pretty good. That would require the posts to be discerned into categories (video, image, text...). I believe they currently aren't?