I told that based on the old sections of DoujinStyle
some people like to keep separated the serious talk from the spam talk. kinda like how RI was to MI, to not annoy people by bumping threads with some stupid/irrelevant thing and so kids have a place to have all their dumb talk, there are people that don't even like touhou joined in there, why?, IDK, but it's kinda like how some people who don't play mugen anymore still come to mugen forums for chitchat.
but I'll give you the news & events/general discussion is redundant & could be merged together.
there are many artists in that community hence the gfx section, isn't only oriented to sprites, (sketches, sigs, fanart in general) , the music/entertaining section is usually like any other in mugen forums, videogames is in general, not just toho, I think being 100% touhou would make a boring forum.
downloads for music & games usually are limited to doujin ones.
of course at the end he/she is the one that decides what to do with his/her forum.