> Basically what's missing is the ability to even guess at the "true" value of cryptocurrency. There's no P/E ratios to consider because the only thing Crypto "produces" is Crypto transactions. It's also impossible to even guess at a floor or ceiling for the price of a cryptocurrency. The only thing that determines their price is human sentiment - a very fickle input.
Interestingly, this isn't really true anymore. Most of the newer defi currencies represent a portion of ownership in some protocol that is actually returning profits.
E.g. Maker is a lending platform for DAI. You can borrow DAI by depositing other currencies as collateral. The interest you pay to borrow is then converted by Maker into a sort of "stock buyback" against its Maker token.
The Maker token has a P/E ratio, as do many other coins. https://www.tokenterminal.com/
To your point though, the P/E ratio for most of these is denominated in other cryptocurrencies, not in USD.