In my view, the point is in that kinds of groups there isn't any leader that rules by giving conversation themes. So the "mess" is foreseeable. 
 
I believe it's not that complexe. You define a theme in advance -> You open an hangout -> You ask people to reply one by one and correct each other whenever someone makes mistake. It's a problem of organisation...

Perhaps, for some people, especially beginners, it provides an opportunity to practice their skills without the fear of being constantly corrected and may encourage them to pursue their seconf language goals. But without corrections, the chance of improving is limited.

I once joined study group for learning English in real life rather than online. It was created by English learners rather than by English teacher. But after a few weeks the study group meet up turned to a place for dating. A few rotten apples spoiled the barrel. I don't expect I can get nothing from something. 

Well, I don't know yet as I'm new here, but so far, the people I've been talking with and I correct each other and help to understand how to say things and that stuff. I'm a bit displeased with the fact some people use this website to make rude comments or try to flirt, but anyway, I think that if you find the correct people it can be really useful, as other websites.

I'm my case, I speak with people to improve my languages and I don't like talking about stupid or empty thing. I want to gain a proper English and Japanese vocabulary. If at the same time I can have a good time and make some friends, the better, but if not and it's just practising, it's good for me too. 

There's a huge group on Facebook called " Polyglots " which in my opinion, is the best one! 

People there discuss languages deeply and there are interesting topics. It's not a group for finding a partner, but you can of course try and be successful, but it's not their main intention. The group is rich on information and other people experiences!