I know you have strong opinions on the topic, but just claiming Bitcoin is fungible when it is clearly not (right now) is imho dangerous. It may lead to Bitcoin-users mistakenly assuming anonymity when it is not necessarily there.
"Taint" is like a religion: it only exists if people believe it exists. If you can't accept cash money without doing a background check, money loses it's value. The same will happen to Bitcoin, and that is the real danger.
Right now some governments are trying their hardest to not have it that way. And are partly succeeding.
Governments can't stop Bitcoin, but they can make people believe they shouldn't trust Bitcoin. That's the real danger, and that's what I indeed have a strong opinion against.
It's worse with the companies promoting the idea of taint: they made a business model out of telling people some Bitcoins are worth less than others. They're not sharing their list, just like governments don't just publish a list of "tainted" Bitcoins. The whole concept shouldn't exist.