Because we're humans, and as a product of talking about C++ on this forum we develop relationships with other users and there needs to be a place to put the resulting irrelevant chatter. If it bothers you don't use the lounge.
IRC is great for finding help. You can ask a question there and get real help. Though doing a search on here you find different users have, at one time or another, made an IRC channel. Though, we do not have an official C++.com IRC channel from what I can remember.