That isn’t the point at all. Zero people say blackmail isn’t real or isn’t done with bitcoin.
The point is that crime is not a feature of bitcoin. It’s a call for the person making this claim to check themselves: do they hate the crime? Or do they just hate bitcoin.
If it’s the first, then their efforts should be towards the primary mode crime is executed: fiat. Spending time and energy on a fringe way to pay for it is silly.
If its the second, then evidence will not get them out of a position that evidence didn’t get them into.