“Look at house prices valued in a commodity (oil,gold,copper etc) rather than USD and the prices are going to appear flat or even falling over the bubble period”
That doesn’t matter because the vast majority of houses are purchased with US dollars coming from US jobs. Has your pay been increasing at the rate the dollar falls? Doubt it. But folks like you and I represent the typical player in the housing market, so the dollar remains the correct metric to use when evaluating the increase in home prices.