If you want to set up a league that plays by your own rules, all the power too you. If I like watching people slug it out with battle riffles better than with all the weapons available why is it wrong for me to hold a tournament with those rules? I agree that players shouldn't be setting the rules, but the governing body organizing the titles or money in question should be completely free to reward whatever behavior they see fit.
The problem, as you said, is when you start thinking that your custom rules are how the game was intended to be played.

I virtually never play FPS games, so I don't have a lot of firsthand experience on this. I'm just going on general life experiences of elitism, of which this seems to be a classic case.