That's true. You never mix any more than you're willing to lose. And sure, it's money laundering. But money laundering in defense of freedom from oppression is OK, as I see it.
I'm OK with that. And it's impossible to avoid, if you're using systems with any chance of protecting your privacy. Also, criminals tend to attract lots of attention, and they're often careless, so they act as canaries.
There is the concern that you'll end up with Bitcoin that's been tainted in one way or another. However, at least some mixing services get coin from miners, so it's clean. And you can check for that in the blockchain.
That's mostly a concern when you're mixing Bitcoin before converting it to meatspace fiat. If you're anonymizing Bitcoin purchased with meatspace fiat, it doesn't matter so much if some is tainted. Or at least, it won't unless tainted coin gets blacklisted.
Admittedly (!) exaggerated, but are you not also providing cover for criminals by doing not essential things (like playing tennis), because criminals would be catched easily if no law abiding citizen would do that kind of things, right?