There's too many threads for this forumbase to suppose, it's more like an asynchronous archive atm. Not that that doesn't have it's good points, though.
I had noticed that, it was one of the aspects of this forum that distinguished itself from others though.
But the forum hardly has the amount of users to actually keep even a small segment of them active.
Though I'd rather digress from accumulating all Touhou threads into a single topic, as this ephemeral forum
There's another forum I'm on that had a very usable method. Allowing only the newer releases to have their own topics and condensing the older titles into a segmented, but still single, entity.
Though it would have to be one that also properly segments the fighters from the shooters.