In some cases I agree that an auction will give you an estimate of what demand or supply would look like at different prices. Northwestern university used an interesting variant of a Dutch auction to sell its sports tickets:
But auctions are often impractical. Auction mechanisms that induce participants to bid their true preferences are complicated, and you're still forced to assume that the auction participants behave rationally and optimally.
In general, the point that I'm trying to communicate is that it's very difficult to disentangle supply and demand: much harder than most people realise.
https://hbr.org/2013/05/any-business-trying-to-sell
But auctions are often impractical. Auction mechanisms that induce participants to bid their true preferences are complicated, and you're still forced to assume that the auction participants behave rationally and optimally.
In general, the point that I'm trying to communicate is that it's very difficult to disentangle supply and demand: much harder than most people realise.