Most people who play WoW don't participate in the activities that provide leadership and group interaction experience.
For an average progression guild there are 1-6 people who could possibly have the opportunity to gain valuable leadership experience, and 19-35 (benchies) who are being led.
And then for every person in a progression guild there are hundreds (if not thousands) of people playing the game that aren't even being led by the leaders.
For most people, all the people they know who play WoW will fall into the non-leader majority, which fits your experiences perfectly. This, imo, is what gives MMOs and other online games a bad rap.