This is mostly irrelevant. Bitcoin "has no" escrow arbitrator in the very same sense that cash (esp physical) has no escrow arbitrator. It's just something you have to layer on top if you want that service, the same way you would for a cash transaction. To the extent that it mimics cash's irreversibility, then of course it inherits the need for third parties when you actually want this kind of reversibility.

(Normally at this point I'm supposed to mention bitcoin's embedded programmable contract system that further facilitates escrow, but I'm worried that bringing it up at the same level would encourage the very same apples-to-oranges comparison I'm trying to get people to stop making!)