What do you use L3 Transparent Proxies For?

Pretty much as titled, what uses do L3's have. If they not only identify you as being on a proxy but also reveal your IP why even bother with them? The only reason I could see is that maybe some sites don't resolve the IP's so then maybe it wouldn't matter. Aside from that though, why else would anyone use them?

honestly i get a shit load of them
and they all go in the same place BIN.