Here are my thoughts on this. I'll preface this by saying that I am a strong supporter of change for the RMT section (example, example). I will keep pushing for the changes it needs until they are done (and for the rules list overall).
I don't understand why RMT requires full rates as answers. Sometimes, one well-founded and well-defended change can absolutely be an answer.
I agree, and I don't partake in converting answers like these. I think that short, undetailed observations should be comments and everything else should be an answer.
However, for as long as the rules page says "only answer if you have notable improvements" etc. this will be tricky to control. I also think that RMT has greater problems to contend with than content existing in comments instead of answers.
While we are at it, maybe add a prompt while people are asking a question to ensure that they are talking about a competitive team...
We already remove anything that could not be justified as a competitive team (under the rules list's generous definition). That happens almost daily.
But I agree that there are lots of ignorant people submitting teams to RMT, and some big rules/culture changes are needed to correct that. Again, stay tuned (and Pokemaster, if you're reading this, please please tell me what you think of this).
... and ban Anything Goes
No, sorry. I agree that AG's lower ladder is woeful (and we get plenty of posts from people playing there), but the correct solution to that is tighter rules around post quality, not banning the entire metagame.
Here is just one of the AG teams submitted in the last few weeks that I would consider to be "competitive" enough. I will have no part in banning posts like those.