As for what Tok is trying to say here (I believe, I could be getting him wrong, hate to put words in people's mouths) is that cryptonote was designed initially to be used with a central authority that holds the "keys".
Okay well that's totally wrong.
Throwing those keys away only makes it impossible for anyone, not even a central authority to verify what happened, inside or outside of the blockchain. The cryptography must be trusted, which kills the whole concept of trustless.
This totally misunderstands the concept of a blockchain. To verify a blockchain (even Bitcoin) requires cryptography. Unless you rely on cryptography, you could easily be given some fake bunch of data that looks like a blockchain but is actually nonsense.
No, not really. I can follow the coins all the way back to when they were created. I can do that with my own eyes, following the account numbers. Nothing is obscured, even when mixing the coins, breaking them up into exact denominations, etc... This is how Bitcoin works, this is how DASH works.
You can follow the coins back how? By looking at gigabytes of 1s and 0s? Or by using a chain explorer which is connected to a node, which in turn only knows it is receiving valid information from anonymous people on the internet by verifying the cryptography? I'm pretty sure it is the latter