Why do some threads disappear?

[Bird]

Why don't they at least notify posters that the thread was moved.

I had responded in a thread that was complaining how Obama changed the labor laws for teens IN 2007. I can't find the thread.

When a moderator removes a thread, the original poster is usually notified of the reason, but not all the others who may have replied in that thread. And poliitics is a prohibited topic except in the politics forum.