No, it's the fault of the manufacturers (and indirectly google, who take take any number of actions to coerce manufacturers to provide updates either more speedily or at all).

It's the user's problem, but for the majority of them it's not a problem. At all.

But for the handful who DO want the updates then yes, it's on them to pick wisely before spending hundreds of pounds on a phone given what we know about the Android ecosystem.