Yes - this is exactly what the silk road did. A buyer would place enough coins into escrow with the silk road to prove he had the funds available to make the purchase, the seller would ship the goods, after receiving the goods, the buyer would unlock the coins from escrow and they would be given to the seller.
The problem here, is that this effectively makes the silk road (drumroll...) a traditional bank. With the monetary controls and downsides that the folks trying to speculate on bitcoin claim they don't want. (The can freeze funds, reverse transactions, run away with your coins, etc)
Further, since traditional mining is out of reach for most folks - there's no real way to avoid having to buy through an intermediary. So when you hear folks saying "Not your wallet, not your coins" ask them how they managed to get their coins in the first place, and how they avoided ever trusting an intermediary with their coins during that process (unless they literally mined them themselves, not as a pool, they're bullshitting you - they trusted an intermediary, and fraud was absolutely a possibility)
I think my real point here (admittedly long winded) is that a large reason the modern banking system functions the way it does is that they've essentially been asked to handle fraud and dispute reconciliation in a world where you're not allowed to resort to rote physical violence yourself. Unfortunately, to do that they require all sorts of monetary controls (The same controls coin enthusiasts claim to hate). But those same enthusiasts don't actually have a functional solution for handling reconciliation in instances where a dispute actually occurs, outside of falling back on the legal system of a government.
Some of them seem to have a mental fantasy of hiring assassins or threatening folks with either hacking or some other "dire" threat, but it's mostly bullshit - when fraud happens they run squealing to the government or they eat the loss. These folks are like a strange variation of the "prepper" crowd - they wish the world worked like it did thousands of years ago where blunt force solved problems.
Thinking escrow services make them a central bank means you're misunderstanding a lot of things. "Central banks" control currency printing, which silk road never did. The entire point of BTC is that being algorithmically controlled. I suspect you just mean traditional banks where people have their checking and savings accounts. But you're still mistaken. Having an arbiter for the money involved in one transaction does not mean you can have all of your funds frozen. At worst you can have a bad arbiter that awards the money from one transaction unfairly. They also absolutely can not "reverse transactions" if you are paying with a transfer on chain. I think you're mixing up "escrow" where a website requires you send them your BTC and they transfer your BTC to someone else for you by moving numbers in a SQL table with actual on chain transactions. With on chain escrow the arbiter can never get the funds, only forward them or send them back.
