Why wouldn't percentages be relevant? If one currency delivers a massive amount of utility and value to society while a tiny fraction of it is used for illicit purposes (i.e. USD), and another currency is overwhelming used for illicit purposes, with only a tiny fraction being used for actual utility, that is a meaningful comparison.
You're not making an argument here, you're just saying "percentages bad, absolute value good". The only argument you're making is that using percentages "hides" the negatives USD, but the reverse of that is equally true (absolute values hides the problems w/ cryptocurrency).
My argument is that the net impact of USD is positive, while the net impact of cryptocurrency is negative.