They call it objective measurement of worth by the market.
That's kind of a silly take considering MC can't measure volume or depth.
Two market caps could be exactly the same, while the amount of USD that can actually be extracted from the liquidity pools could be wildly different depending on how many buyers there are backstopping the current price.
I agree that using a single measurement like Market Cap and extrapolating conclusions about vallue and future potential is very faulty logic.
Your examples are some of many.
I think characteristics like utility and community are much better measurements and the success of BItcoin and Ethereum in either community or utility suggests those characteristics have much greater predictive value of value or future success.