Admittedly, I use "This." fairly often. If I see a post that mirrors my thoughts about a topic in a thread instead of posting the exact same thing, I'll just use a "This.".
Frankly, some people get awfully pissy around here if a lot of people express the same negative opinion about a topic and sometimes it can be considered trolling or flaming because it was expressed a lot. If the opinion is untrue than I can understand why people would get upset.
A "this" sometimes allows you to you agree without catching flak for it by community or the mods (haven't seen that with this mod team, though).