How about modpack specific forums? I'd much rather post to a DW20 1.10.2 modpack tech support forum than the General FTB Chat forum. Seems like that would reduce some of the clutter.
Well yes, a lot like that. But I don't see that forum from https://forum.feed-the-beast.com/forum/? And I see that your pointer is for mod-specific bug reports. But what about general chat or other such queries? Don't get me wrong, I really like your pointer to this forum--thanks a bunch.
Having lots of different sub forums for all kinds of modpacks and other things only isolate people and will reduce traffic to them. It also burdens the Moderators considerately, by having to constantly browse around more.
It serves no purpose having a lot of inactive boards. Recently I moved the Modpack Bugs boards into Tech Support because there was an obvious crossover with 2 bug reporting areas. Strictly speaking I think Tech Support was historically used for launcher bugs and ModPack Bugs was used for modpack errors. If you'd like to just generally talk about a pack then General Chat is the place to go.