> haven't had to prove a single thing
Even in your jurisdiction, you may soon have to. From the linked article, you can infer that you got lucky - your attempt to cash out might have been stopped by an exchange, if you did it a little later or with a little dirtier coins.
> and if I had really wanted to I could have traded into fiat via direct trades using sites like localbitcoin.com or similar
Good luck meeting random strangers and trading BTC for cash with them safely AND anonymously. You're lucky if you get even one of those two.
> Guilty until proven innocent is an untenable practice
Tell that to financial crimes investigators, whatever they're called where you live. As I said, they don't mess around. They're not reasonable. The price for operating in the legal economy is that you have to be able to account for your assets. The exchanges don't do this because they want to, but because they have money laundering cops breathing down their necks - and you will too, if you're silly enough to try to cash out significant amounts through localbitcoin or similar.