Remathilis
Legend
That's like saying you wouldn't watch a movie unless it's part of a Cinematic Universe. Sometimes the best stories are self-contained.From the DM side, perhaps.
From the player side, I'd find a hard-line AP constraining as all hell after a while; even more so if it was known ahead of time that the campaign would end when the AP was complete and that we couldn't go on and do other things in the same setting with the same cast o' characters.
That said, nothing stops you from having multiple APs all set in the same world (like Paizo has all APs set on Golarion) or reference prior adventures. I mean, plenty of adventuring parties have also moved on from one AP to the next, depending on the end level.
Nothing you have referenced is unique to sandbox play.