I think the rule-of-thumb of using 3x, 4x or 5x income multiplier is a bit outdated; it needs to be adjusted to reflect the current low interest rate for a more realistic comparison. If 4 times income was used when the interest rates were 8%, then shouldn’t the multiplier be something higher if rates are at 4%?

Assuming 0% down and interest rates at 8%, hh income of $63,400–> $317K loan –> $2,326 mortgage payment

A $2,326 monthly payment @4% means one can borrow about $500K

That tells me the multiplier for the current interest rates should be closer to 8x income than the 4x or 5x rule of thumb.