But if that's the real reason why people advise not to sell bitcoin on paypal then won't that be easy to get around? You can agree with the buyer to sell btc but on paypal make sure the note says you're selling some random item and then you can ship the buyer an empty envelope just to show a tracking number on paypal but the buyer got his btc and you got your $$.
Selling btc in that way is like selling pretty much any other item but people seem to get extra paranoid when it's btc being sold.
I didn't say buying goods with paypal was perfect. it is obviously a flawed system, and if you read the bitcoin white paper one of the reasons for a system like bitcoin is to rely on the reverse type of trust meaning customers trust one seller or shop not the shop trusting many customers.
selling goods has for paypal always been based on trusting the shop, you see the reputation and buy from it, and that scenario when they send an empty envelope is rare and can easily be proven because an envelope with goods in it is heavy and there are some post office regulations that may help proving that easier.
in the end everything comes down to trust between two parties and in bitcoin an escrow comes in.