If chain analysis is a scam how do you explain cases like https://www.justice.gov/opa/pr/south-korean-national-and-hundreds-others-charged-worldwide-takedown-largest-darknet-child ? Those who got charged do you think were innocent and the deep bad state just decided to flip a coin and charge random people ?
I agree that someone can't be 100% certain all the time but there were cases that chain analysis led to child porn rings , especially in cases where the users were ignorant about how blockchains work .

As for the mixers , it's sad to see many people here claim that mixers is a tool to protect privacy , that kind of users that have nothing illegal to hide are just providing exit liquidity to criminals . As a proverb says "when you pee in the sea you will find it in the salt" .