And the video isn't my experience. I've seen people drift away in every expansion. Probably get the most alone in TBC when my small guild broke up after the tank and healer left, and most of them drifted away.
Though my experience of the "community" has never really been that great tbh, in that I just don't bother interacting with anyone outside whatever guild I'm in.
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Most people I've seen leave have never given a big goodbye tbh, I'd say friendships have always been transactional in WoW, for the most part