I see two. This may be a good reminder of forum policy, so although I wasn't involved, I'll outline the two rationales (as I personally see them) for the deletions:
First: "+1" and "^this", by themselves, and with no additional commentary, are frowned upon as content-free posts.
Second: There was a thread where the original post mentioned Islamic fanaticism, leading to several more posts about religion. Almost all of the subsequent posts that dealt with religion were removed, and the thread was closed. Religious discussions almost always turn into messes. TFL's staff don't like dealing with such threads, so they are usually nipped in the bud.
“Compleχity is a symptom of confusion, not a cause.” —Jeff Hawkins