Very true, but couldn't you say that about any p2p marketplace/selling website (like Craigslist)? If someone's the harass-y type, I doubt they'd be bound by platform
They sure are bound by the amount of information you give them.
On Facebook they tend to have your picture, full legal name, social circles, place of work and where you live from the start.
I know plenty of people who use online markets pseudonomously (and also break fb policy on that), and meet in public places for the money/item exchange. It's normal here to only share first names in a trade.