The illicit drug trade far exceeds the number of ransomware events and they use almost exclusively fiat.
I agree, using the argument of "x is a tool for illegal activities" is brittle because you could say that about literally anything.
You could attribute the same thing to Amazon and Google gift cards being used in scams.
When financial instruments are primarily used for licit activity, we tend to add features that make illicit activity more difficult but accept that some illicit use will occur. That's why we still have $100 (but with serial numbers) and don't have bearer bonds any more.