You're not factoring in denominated units (and subsequent rounding at send) and "dead change" being sent to the network to remove linkages in future tx's.
It was a simplified example explaining transactions in general. Remember: the issue we're discussing is the average user deanonymising themselves through inadvertently. Dead change and denominated units do not solve the problem when the user has 50 DRK in their account, they send 20.72368 DRK to pay for some dodgy item, and then because they have some crisis they empty their wallet and deposit the entire remaining 29.27632 DRK on an exchange. Normal actions resulting in unavoidable and unwitting deanonymisation.
Yes this is a problem when the wallet can have "standard coins" and "anonymous coins", you can accidentally send wrong coins.
There should be two wallets imo, the other one can allow only "Darksending" and the other wouldn't have mixing at all.
Good point....or the wallet needs to develop to more clearly show how funds are mixed and associated with transactions. I guess the argument is that better anon, e.g. XMR doesn't have such issues, which is fair enough...