Let me ask a general question. Lets say that in Risk, owning just Greenland would give you automatic +10 reinforcements every turn. That's clearly stupid, unbalanced, and unrealistic. But would you blame the player for taking advantage of it? No! It's NEVER EVER the player's fault if they take advantage of rules in the game. It's only the players fault if they circumvent those rules (3rd party software/aimbots/brightskins, etc.).
Tweaking graphics settings is perfectly within the rules of the game. Unfortunately it gives a clear advantage, and so EVERYONE SHOULD BE USING IT if you care at all about gameplay. You are not allowed to complain about other people using it, it's not their fault. Players have to use it in order to be on equal footing. Change the game so that this isn't possible. I'd complain to the designers. Make a setting on servers that forces you to have certain settings turned on so everyone can enjoy the experience.
In a game where spotting the enemy is almost more important than anything else, you are handicapping yourself by not tweaking graphics settings. If you are OK with that, fine, but you may not yell at others who choose not to handicap themselves. It's the game's fault, never the player's.
So While I agree that this is stupid, and I am not going to tweak my game to the level of the OP in that other thread, I blame that game and it's designers. I don't hold it against other players or deride them for being "competitive jerks." Competitive is not a pejorative term, it's the ultimate level of gaming that not everybody aspires to.