If there was more supply, prices would stabilize somewhere lower. Given enough supply that point would be somewhere one income could support.

It's the constrained supply paired with high demand that drives prices up and requires multiple high incomes to compete (especially in places where this has been taken to the extremes because of NIMBYism and entrenched anti-build regulation/incentives).

what does that matter aslong as your bank has approved the mortgage. I don't see why seller would care.

are you saying that ppl are bidding for mortgages that high that bank needs both of their incomes? wow.