You do see tests done by players, but unfortunately it's rarely done with the major sites. You also see people complain about this all the time on various forums. Their system scores perfectly on everything benchmark, but in Arma, WoW, GTA V they get low FPS in specific areas (and everyone gets those). I also experience this a lot, and used to be a WoW raider. A lot of games seem to have spots which are CPU crushing.
There are a couple reasons we do not see review sites benchmarking these spots; 1) many are in multiplayer scenarios, which are unpredictable and hard to reproduce results, and 2) it would seem most benchmarks setup, are designed to push the GPU, and they simply choose not to create new benchmarks for CPU's.