“As I understand it, nobody knows the value of their assets. Not even themselves.”
Exactly because there is no orderly market and only a market determines value. Plus if, err when, they get valued (i.e. forced into a market) they will be marked down. That is the problem that had to be fixed. Nobody knows what the assets are worth so nobody trades them so they become worthless and the balance sheet of the holder goes south and then nobody will do business with them.
something is only worth what people are willing to pay to obtain.
value is determined at the point of transaction.
(see also: only those who painic in a stock dip lose money)