Purchase price is not rebuild cost
On a new build the two look close enough that people use one for the other. They are not the same: the purchase price includes land, and the rebuild cost includes demolition, debris removal and current code. Setting the dwelling limit from the sale price is the standard error in a new subdivision.
Builder warranty is not insurance
A warranty covers defects for a defined period on defined components. It does not cover a fire, a storm or a liability claim, and it expires. Treating it as cover is how a gap opens in the first few years of ownership.
The Valley exposures still apply
New construction does not exempt a house from monsoon, haboob or heat. It does often mean a newer roof and better sealing, which helps, and it never means flood is included, because flood is excluded on every homeowners form regardless of the build date.