Justin welcome to ECN.
I take it your reference to 310.11 was about losing the required marking if the outer plastic comes off?
That got me to thinking about it so I went down to the basement and stripped some 12 AWG THHN of the plastic sheath.
One roll the labeling came of with the plastic, the other roll the labeling was on the inner layer and stayed in place.
I guess it depends on who makes the wire.
Bob