This is standard HN moderation. When a subthread veers away from the original topic and also toward something more generic or ideological, we moderate the subthread as off topic. That caveat is important, since off-topic tangents can also be whimsical and sometimes more interesting than the original discussion. But on HN, 'generic' and 'interesting' are incompatible, and the generic stuff tends to take over the concrete if you let it (+10x when the material is flammable). Therefore we don't let it.