I suggest renaming this to "some users report Engine not utilizing CPU correctly". Looking at the references it does not appear to be confirmed that its actualy an issue with the engine, it could be an issue with some users machines. Also there seems to be a misconception about cpu cores and gpu being used 100% by a game. This is actually fairly rare and its usually only cpu burn software that can drive a core to that kind of maximum ... this is pointed out on the thread - https://forums.bistudio.com/topic/138999-low-cpu-utilization-low-fps/page-3#entry2260200
Topic on Talk:Arma 3
I don't know if you play the game, or have friends who play it; but the game runs like crap for everyone.