I don't think were really focusing on the actual points of Josh's video other then having years worth of content and steering into AI talks for some reason. (Ծ_Ծ) ~?
The video is more about how established MMOs like WoW and XIV with years of content and bigger player bases are setting up expectations that new/newer games can't currently fulfill, making developers leery on making new MMOs (especially with the amount of money it cost to make an MMO).
MMO players will general stick to one MMO as their main, get bored or burned out of it, go "vacation" in newer MMOs, get bored over the lack of content (because we expect years worth of content, even from newer games) and community, then go back to their main MMO. We see this in XIV when a new expansion releases: New expansion, population surges. Expansion ages, populations decreases. Repeat with the next expansion.
MMOs as a genre are also designed for people to treat their main MMO as a hobby or second life, using their time investment and the drip feeding of new content to their advantage.