Kbin is pretty good for this. Every magazine has two tabs: one for microblogs, and one for threads. The administrator of the magazine can choose relevant hashtags, and all federated posts from the fediverse containing the hashtags will show up in the microblog section. People end up in kbin communities just by making themselves discoverable with hashtags, they don't even need to know what kbin is.
There are, as far as I can tell, two problems:
There's no combined view showing both posts and microblog. As a consequence, the microblog is often neglected.
Federation doesn't work well - you only see these posts if you're viewing it from the same kbin instance as the one you're visiting from. In effect it's basically only useful for kbin.social at the moment.
Still, both of these things seem like they could be resolved, and it's a very neat solution. :)