Im personally doesnt see any “whitewashing” effect on Insurgency: Sandstorm screenshoot. Maybe a little lower contrast because of postprocessing.
Also, im defenitely doesnt see any “sign” of UE4 on that screenshoot.
Fortnine may looks like “Disney catroon” cause Epic trying to achieve exactly “that cartoon look” and make it good, but not because of some sidefx of PBR rendering in UE4.
But it’s ridiculous! 
No one care what engine you use. If you game good - its a good game, if you game bad - its a bad game.
No one will say - “Meh… so awful gameplay, AI and storytelling but look at the picture! Looks like they dont use UE4! Wow that game are awsome!”