Expanded Episode Question

Why do they always say Sidewaysville is ‘if the 815 landed’ – when it’s quite clear the life of the people who got on the plane is very different than when got off? Ex. Jack didn’t have a kid getting on the plane and Locke (and Ben’s) dad’s were super jerks.

Wouldn’t it be better to just say “Sidewaysville is what would have happened if blowing up Jughead worked”? Then we’d just have to follow a thread as to why Ben’s dad was so bent about Ben’s mom dying if Jughead was never exploded, but not so much when they got off the island (perhaps he realized how important Ben was to him in near-death?)

Is this some kind of clue?