Wasn't the whole point of tags to remove the "silos" of the forum? Why can't I post a new topic in both #Bungie and #Community? The beauty of a tag system is that it understands that a single idea can fall under many categories. If we're to embrace a tag system, let us use it to its potential.
Well, it was like that originally, a lot of people found it confusing and that's why they added primary tags as forums. That's why you'll see some threads from the beta in January existing in multiple forums. I don't see them removing it anytime soon though.