Yes, it's a fair question. You pointed out fraud, though. Some sellers don't trust buyers. They don't want to absorb bad debt losses because it's a hobby for a lot of people, and they don't want to be burned.

You didn't accuse anyone of being idiots, but others have posted responses along those lines.

I'll bet a lot of people complained when doctors stopped accepting chickens as payment. Business is evolving, and PayPal provides a high-tech safety net for a lot of sellers, as well as allowing them to accept credit card payments without setting up a credit card system that requires certain minimum sales levels. Some sellers are just more comfortable with PayPal, despite the costs and limitations.

I accept checks, money orders, cash & PayPal. I dropped one on-line payment system years ago because it charged fees to the buyers as well.