I'm not sure what games you have played, but most games with an anti-cheat system also have a SP side. Quake 4, Prey, COD Series, Doom 3, F.E.A.R, Rainbow Six...and more.
I also think most of the problems with GRAW is the engine. The very basics for MP are missing, from the simple fps built into the game to more important demo's and anti-cheat system. I find it hard to believe that UBI would tell GRIN to remove anything from their engine.