It's in HN's DNA to have a single community. The path you're talking about leads to subreddits, which would make for a siloed kind of site, i.e. one that is broken into silos rather than being in the same world. This is an important point, because it touches on the what-HN-is-and-isn't thing.
HN is a community for the the intellectually curious, who come here for a wide range of interests (some of which have political aspects, of course--there's no getting away from that). But there's a different kind of users, ideologically committed ones, who use HN primarily for political battle. That's not something that sits well with the purpose of this site, as I tried to explain above.
Those users really want a different kind of site than HN, and need to find another, or maybe start a new one. Plenty of new sites have spawned from HN; that's partly a function of our not trying to be all things. HN has always been in the lucky position of not needing to grow for growth's sake, so we're happy when people who want a different kind of community find it, or create it.