What are "routine escrow mechanisms"?
There are certain sorts of escrow that are very difficult to implement without a trusted party. For example, an escrow system that only sends along the payment when the seller has provided proof of shipping would be impossible without a trusted third party.

However, if we change the escrow system a little bit, then we can implement it without a third party. For example, suppose we say that the buyer and the seller merely need to agree about where the bitcoins are sent. That is something that a decentralized network can check for.