I had been wondering much the same thing. On most forums, if you click the control panel button, you only get the active threads listed, but if you then click "subscribed threads" in the control panel you get a continuing list all the rest; that's why there's a hyperlink called "Subscribed Threads!" If you do that here, you get "There have been no new posts in the last 30 days to your subscribed threads" - even when you click "View All Subscribed Threads"!!! That response doesn't make any sense; #1 I haven't been the last post in those threads, so there should be something newer than my post in the last 30 days, and #2, I'm not asking for new posts anyway; that's what the control panel is supposed to provide. I want all threads at that point so that I can go back to an older subject - maybe to look up some information or something.
Another thing to consider; there's an option to subscribe to a thread by clicking a button at the bottom of the page; I assume that's to enable keeping track of a subject without actually posting there. Will searching for "all posts by this user" give you threads that you subscribed to using that method, since you didn't actually post? If not, then what's the point of the "Subscribe" button if they don't show up under the "Subscribed Threads" list?