While there are few mixer which claim it'll pass AML check or can be deposited to centralized exchange without problem, it's hard to achieve that in reality. There are many system used to check whether Bitcoin comes from illcit source and nobody know how exactly it works.
I think that whole AML score propaganda is promoted by exchanges and blockchain analysis companies to make money out of thin air on platform and outside platform, I won't be amazed if there is a mixer that's actually owned by exchange or companies that run blockchain analysis. AML score is bullshit, it doesn't tell whether money is illegal or legal, it only tells how well you hide your identity but it's also paradox that it's not completely like that. Blockchain analysis companies often make mistake and their AML score calculation doesn't make sense because it can turn on false positive on completely clean transaction with clean history. It's a new way to market and make money for mixers but I can't blame them, they supply the demand.
It's one of many ways to remove connection/link of your past Bitcoin activity. And while it's true the fees is high, few people use this method either by doing it manually or use mixer which claim to do that for you.
What's the difference between sending 1 BTC to mixer and receiving 0.096 BTC from mixer compared to sending 1BTC to mixer, converting it in 226 Monero, then converting 226 monero and receiving 0.096 BTC. What's the difference? I send bitcoin and receive bitcoin. If it's an instant exchange or withing 24 hour timeframe, I think it doesn't make much sense.