That may work for common topics, but it does not appear to work for niche ones, at least in my experience.

If I want to find a particular user-run forum on some obscure bit of some hobby, "<hobby name> <forum topic>" brings it up. But if I type out "Forum for <hobbyists> discussing <topic>" I get... a random selection popular of fora where someone has mentioned <topic>, often in passing or with minimal information.