I didn't get the impression that "humanizing" was much of a concern.

plays it out of time

Rest of the band likely just got used to his idiosyncratic playing and adapted.

At some point I think we have to put the “it was a freak accident that was repeated with precision over and over, forever” argument to bed.

Probably we limit ourselves a lot if we're too confined to those without being able to express our energy

But someone who is trained explicitly to play exact integer divisions will have trouble expressing their energy as much

There is a difference between the crude musical notation and how it's actually meant to be played - a notation showing 4 quarter notes in a 4/4 beat does not imply that the correct way to play them is to literally have 4 identical notes with idential gaps; even without any explicit extra notation (which indicates significant changes) there is an implied understanding that there should be a variation in velocity (and, for a skilled practicioner, not a random one, but placing slight emphasis as required) and a variation in timing (again, for a skilled player not random but e.g. depending on the music genre a slight shuffle or an intentional shift of one beat); this variation is not a flaw of imperfect execution, but required to properly play the music as intended.