Because its going to take several months of dedication and hardwork to get back into shape and peak performance again and there is no point in doing this if there are 20 gow players left. You cant quit playing something for 10 years and expect to be just as good as soon as you start playing again, it doesn't work like that. You need time to get it back and for what? I am enjoying LoL and see no reason to leave the biggest game in the world for some old game with 20 players left. If I see the game become somewhat popular again, I will return.