My read on the article is that they're considering two different frameworks: one where everything that comes out of the mixer is considered fractionally dirty based on the inputs. Or, randomly picking an output and tainting it 100% under the "FIFO" method.
The idea isn't necessarily to de-anonymize the transactions here but to disincentivize people from using mixers. Either a haircut kills a portion of your value, or you lose it all, the idea is you won't do that again.
That doesn't change that legally it still kills all your money, and creates a liability on the person who put in the dirty money. If you figure out who they are it's all you, you're welcome to sue them. If not, you've learned a hard lesson.
Again, the whole problem is that the bad actor can pass off their stolen bitcoin before anyone knows its tainted. So it doesn't matter if you didn't use a mixer, if that bitcoin ever went through a mixer it could potentially be a live hand grenade. People could just mix large numbers of bitcoin periodically so everything is suspect.
You're not solving the problem, you are just introducing new problems that affect other people in the hopes that the entire system becomes unworkable.
In much the same sense that you could abandon your house when you have termites: you're not solving the problem, you're just avoiding it in an incredibly inefficient manner.
