I have lined up further ahead than what I was permitted, and also simply lined up at the wrong floor stand. After 30 years of flying WN I suppose I have been equally guilty and generous, with other pax, giving up exit rows to exceptionally tall fliers.
In reality, I see little difference on most of my flights. I can usually get exit row seating except on afternoon flights, where the flight may have many thrus.
Am I seeing it more? Not really, but I continually see it on flights that seem to attract amateur fliers.