Everybody wants to get lots of feedback, pushing your game to other people does not take away awareness from other peoples games. If two people play the same game, one game doesn't get highlighted just because of their count of ratings. Neither does this happen during rate4rate, everybody gets equal chances on gaining ratings and feedback. So this argument does not make that much sense from my view. And yes everybodies time is limited, but game jams are mostly about having fun and learning. Just limiting yourself to games with low ratings, can be fun, but it's just not the whole experience. A lot about getting reviews is also about the appearance of your game. If you have a decent game with webgl build and a nice thumbnail, it's probaly enough to get 20+ ratings in the first 3 or so days. I see a lot of people that just don't put effort into their appearance of the game. It's just another part of game development, if your game's appearance isn't good people won't be intrested and won't play your game. And not playing other people's game just makes it worse for you. This is something too that the developers should learn. Pushing your game is just a part of a jam, just like in the real world. Of course there will be someone that finds your game and maybe play it, but it's also a lot up to you, wether you are dedicated enough to try and show other people your game. But of course there are always exceptions, but this is my estimate on the general jam community. People that play more games and try to advertise for their game usually tend to be the ones getting more ratings. If you help others more and try to advertise your game, you usually end up getting more reviews. The more work the better the result. Playing other peoples game is also a passive way of getting ratings.
I agree that helping others can improve your own skills too, especially when explaining topics, but it's in my opinion important too that you actually gain something too, especially in jams. Jams are a lot about lifting each other up, if the other person isn't willing to return the favor, it's probaly time to choose another person.