Trying to protect the rating is not the only reason strong players don't often play against lower rated players. Most players play chess for the intellectual challenge. What's the incentive to spend time on a game that's not challenging?
On the contrary, I've seen people in the forums who say a high rated player hasn't really earned their rating because their average opponent rating is low.
Does anybody know why a strong player(2000 or above) is reluctant to play a weak player(1700 or below)? I realize they want to protect rating but if the numbers really speak they shouldn't have anything to worry about. And if they're worried if somebody is going to cheat(chess engine) to boost rating they should be able to tell or not. What do you think?
Personally, I love playing really strong players and getting a serious whoopin'. But that's just me.