"If the assailants had been required by OfferUp to provide even the most basic of legitimate personal information then things may have turned out differently."

The writer's conclusion that OfferUp should be doing background checks on every seller doesn't seem scalable at all.

That said, the AirBNB model (authentication with social media, use of real name in listing) would be a big step toward user safety over Craigslist.

Close5 would be similarly risky if they don't vet either.