Tumbling crypto never made sense to me: "I don't want the government to know that I made this $50 selling weed, so I'll trade it for $49 dollars from another we

Tumbling crypto never made sense to me: "I don't want the government to know that I made this $50 selling weed, so I'll trade it for $49 dollars from another weed dealer to make it look 'clean'!" Shouldn't you expect that most people paying to use tumblers have a reason to do so, and thus the vast majority of coins from tumblers are tainted as well?