Feel free to report any posts that should be in a different subforum. Erm, I'm moving yours too
I definitely think that the General discussion is overused and has always been
I think part of the problem is that the title doesn't always make it obvious that the question is about English, as opposed to a FIGS language. (nobody would ever ask a question about Finnish grammar/usage and not mention in the title which language it's about)
And questions from newbies mean that we're doing well in google's rankings, which is great
If we were to start a separate subforum, I think it's better to name it English learning rather than Grammar questions. But this is not up to me to decide. However, questions that can be applied to other languages (such as the one about twitter) should be left alone, in my opinion.
Also, don't forget it's the time of the year when people who are taking obligatory English classes at school/university may have to prepare for exams or just take a break from other languages to improve their English grades. In summer there are generally more posts about learning for fun.