Not really accurate. I've gone back in past expansions to complete content or do things that would have been experienced had I had an alt or alts to do them.
Especially as it relates to story, that stuff can be done later on freely. I don't feel a compelling need to make alt characters so I can "experience" the story from a different covenant perspective. Youtube exists for a reason. I didn't get into high end raiding until TBC, but in vanilla i watched youtube videos of the content and it helped me aspire to see it for myself in game.
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Also, this^.