If it was publicly known that you had exactly 1 ton of legally acquired gold in your house, would you feel perfectly safe sleeping at night? Is there not 1 sicko out there that would be willing to torture your family to find the combination to your vault?
Plausible deniability exists here. It's called wanting privacy, and there's perfectly valid and non-criminal reasons to want privacy, despite repeated false claims.
Here is the problem. Many cryptos are not actually anonymous. If somebody has somebody's wallet address, they can look into tracing information about them like their net worth and their purchasing history. Even if you were smart enough to use a different wallet address for each transaction, you inevitably have to spend money to live or send money to others and then you can be traced. As tools grow more sophisticated and more data about wallet address ownership gets out there, the more at risk people will be. And once your identity gets out there, there's no shaking the ability to track it short of some form of mixing or obfuscation. In an of itself, mixing or trading to obfuscate your identity shouldn't be considered a crime or unreasonable in the slightest.