Full screen works fine for small screens (I use it a lot on my 13" Macbook), but it just doesn't work as consistently for a large monitor. It's uncomfortable to use most apps in full screen on my hidpi 27". It really depends on how these apps present information, but in most cases, either the focus info is not centred, or it would require to much eye and pointer travel to interact with a full-screen application. Either case, the ergonomics are poor.
And you really don't know what "cognitive dissonance" means. Just re-stating the same false ideas over and over again, in condescending and unpleasant ways makes you seem like an ass. Do a search instead, learn something new.
Thanks for the pointless post!