Varied experiences is one of those things that's either a bug or a feature depending on where one stands.
The idea of users having completely different experiences is a problem when some of the experiences are lackluster, BUT, on the optimistic side (maybe a theoretical side) that also frees UIs to give users different experiences they'd prefer.
I do like the idea of application developers tailoring their UIs to the needs of different users, empower users to look for the experience they want, even if it's different from someone else.
That being said, yep, it is a problem that many of these applications are struggling to really fulfill that promise.