To me a "great" system would be independently verifiable. As in, you appraise your house and you then find you can sell it within 5% of that number. This is not how it actually works, though. The appraisal is often
spot on the offer you got for your house, because the appraiser clearly knows the number they need to hit for the loan to go through.
Maybe the system is great for some slice of the market, but for owner occupied detached homes it's pretty shitty.