OP does not know what he is talking about with his generalized blanket statement.
5 letter pronounceable domains can be worth $300 or 3 million depending on what it is. Technically a 8 or 9 letter domain can be the same.
It is, and always will be, based on the end users purpose for the domain.
In my opinion there is only one thing that establishes the value of a domain. Does a large company, or rich end user, have a need for it. A poor end user cannot afford to pay a significant amount so all other aspects of trying to establish value for a domain go out the window without an affluent end user.
That is why knowing your end user is the most important part of due diligence when selling a higher value domain.