@rainingsnoring When you say valuations, you mean mortgage valuations, right? Which adds a layer of complexity, as the bank is interested in what the next buyer after the current one might pay, in the event of foreclosure. But even then, LTV is a bigger determinant of the bank's risk than house price indexes.
There is also a significant difference between the best possible price a house could achieve, given unlimited time and budget to stage and market it, versus the best price a seller can realistically achieve if they need to exchange and complete 12 weeks from today and expect to live there in the meantime. Those are indeed two different prices, but they are not attributes of the house. They are attributes of the seller and their specific circumstances. If a desperate seller sells in a fire sale to a cash buyer who has dreamed of owning that house their whole life and intends to live there for another 40 years, then on completion the house will instantly appreciate in value by a huge amount, regardless of economic conditions at the time.
It's also not that I'm assuming a perpetual sellers market (although there is some truth to the maxim that they don't make land anymore, and the population needing shelter continues to rise year on year), it's more that I don't accept the concept of 'needing to sell'. It's always a choice. Houses aren't perishable goods, and they have utility providing accommodation in addition to having intrinsic value. The rental yield effectively sets a floor price, below which no house will ever fall.
Ultimately, though, I simply don't care what an aggregated opinion of people who aren't going to buy my house think a buyer should pay. I'm only interested in what the person who is going to buy my house will actually offer for it. If, and only if, it's greater than the value I place on it, then that's its value. If not, then the price at which I would have sold it is it's value.