While your idea is valid and could potentially clear up the RMT section, I think it would have a negative effect. In my experience, the best way (besides 1 on 1 tutoring) for a new person to learn is by either getting well-explained criticism on their team, or reading well-explained criticism on a different team made by somebody who is as experienced as they are. That goes away when you're only allowed to post if your team is nearly perfect.
I learned a lot of what I know by reading people say "your team is gyarados weak because it can set up on Scizor and Infernape, use Dragon Dance, and KO your entire team. You can use defensive rotom-a or Vaporeon to counter it. I would choose Rotom-a because it can take a Waterfall from Gyarados after it has used Dragon Dance once, and then KO back with Thunderbolt. It fits best in place of Pokemon X because all X does is stop Pokemon Y, which Rotom-a does as well."
Well-refined teams made by players who actually know how to build a near perfect team won't receive such comments. Instead this will happen: "a team with a well played Salamence/Lucario duo could give your team trouble. Make sure you don't let Gliscor take damage early and you could use Choice Scarf > Specs on latias to outrun +1 Mence."
If I'm a new player, that just went over my head. I don't care about what the best, >1500 CRE players are going to do to me, I just want to be able to beat players around 1200-1300 CRE like me, and possibly put up a decent fight against somebody higher up.
Sure, often people with low post counts are inexperienced and post rule breaking RMTs, but some are actually trying to get better, and just can't quite get their team right. If all inexperienced people are prevented from posting, we're kinda just magnifying our supposed "elitist" attitude. If mods have to preview every thread before it is posted, RMTs would surely back up and by the time your RMT is posted, you may not even use the team any more. Either that or we would need like 20 RMT mods to make sure there are always a few on hand who are free.
tl;dr: I'm against this because even though it might help in some areas, it will probably make other areas worse.