Some players are beginners and may I want to play other beginners online. Some players are mediocre players and may want to play other mediocre players. It's not all about wanting to fight the best players online. I don't think it would be fun playing someone much worst or better than you. It would be convienent (instead of going to some website) to have matchups similiar to many online game websites like Pogo.com where I can choose a room based on skill level and see potential opponents' ranking and have the option to sprawl if he/she inclines.
I remember I used to go to Pogo.com to play checkers and improving my rating pushed me to be a better player. Sometimes I would play Grandmasters to learn from them, sometimes I would play weaker players to experiment. After several months I reached Grandmaster. I am pretty proud of that achievement. I think this is more rewarding to most people than achievement points. I also think people would be playing the game even more using such a match making concept. And isn't that would any developer want?
And geez, how is competing to have a high rating such a bad thing? It's not all about ego, but so what if it is?
