All I said was if I bought a mount, I probably wouldn't sell it to someone else just because they claimed it was theirs and especially not if they started sending me hate mail.
You are right. A person who bought a stolen item doesn't have any obligation whatsoever to sell it back to the original owner. After all, like you said, they may not have any proof.
But some decent people would. This world isn't that big, players, especially the higher level ones, are bound to interact so people know people or know others who do, and have some impression if someone is telling the truth.
In any case, everyone has their own take on what to do if they learn that an item they bought was stolen or scammed. It's all about a person's interpretation of what's right and wrong. If it was me, I'd sell it back. But that's just me, and I'm not saying it's right, but in my point of view it's the right thing to do.
There are two types of people in this world: Those who crave closure
A business is more profitable if they don't gouge and piss off customers.