Home ownership and mortgages are one of the primary drivers of economy because of how many purchases and consumption it is causing. This is both the construction (building materials) and the consumption (furniture, etc.) when the new owners move in. The wealth effect from rising prices is then also driving confidence and consumption. It depends on which aspect you want to focus but all of these things are measured differently by national statistics bureaus of countries, which the central banks look at (in some cases undertake themselves) and change their policy.