What year was this?
Except you're taking about before 2011/2012, I see no reason why one should go to a social platforms like Facebook to transact with total strangers, with the high risk of getting scammed and zero protection against it happening
I personally can't generalize all FB users are scammers and I think there is no platform limit to reach more and more consistent customers. On my country, FB is still a popular platform for the lower middle class to transact anything in the same area and obviously it will be placed on p2p dealer personal web info pages.