*snip*
Escrow is used to make sure the buyer of BTC receives the BTC. It doesn't stop a chargeback but neither does receiving first.
You might think, oh well paypal is the only one at lose here but why should we let these PayPal scammers who have NO interest in BTC get away with stealing ANYTHING here?
Let's say Alice is selling 1 BTC for 300$ to Bob, via Paypal. Bob is a scammer.
Scenario A:
They decide to use an escrow.
Alice sends 1 BTC to the trusted escrow, Bob sends 300 $ via Paypal to Alice.
The escrow releases the 1 BTC to Bob.
Bob files a chargeback on Paypal and gets his 300$ back:
End result: Alice has nothing, Bob has the Paypal money and the Bitcoin
Scenario B:
They decide to not use an escrow.
Alice sends 1 BTC, Bob doesn't send the Paypal money.
End result: Alice has nothing, Bob has the Paypal money and the Bitcoin
There is no difference, atleast in this scenario. Even if you reverse it, such that the person offering the Bitcoin is a scammer, the Paypal user can always rightfully chargeback.
The person using Paypal to send money, is always perfectly secured against scammers due to the ability to chargeback and can scam at will too.
Your insistence upon escrow would make a difference in any BTC only transaction, but not here.