Do New Players to MOBAs Actually Retain?

I am leveling a new account with my brother who is new to MOBAs and I forgot how awful the leveling experience is. When my brother plays solo he is getting stomped every game. From my experience playing with him 95% of players are not new to this game and completely stomp new players. Beyond that people are telling him in chat how awful he is and are being extremely toxic. I could not imagine being a new player and sticking around.

Is there anything riot can do to make the grind more bearable for new players?