I'm a bit baffled.
In this section what counts as a "thread derailment"?
On some threads some people post "off topic" posts that are allowed to stand.
On others, someone posts something and there is a immediate "pile-on" and they are told that they are "derailing". This is usually followed by a load of nasty remarks and sarcasm, so mods have to remove the posts. (which "derails" the thread anyway)
It seems to me it's "one rule for one" etc