And it is mentioned as such in the article too that "Clear History =/= Delete History"
> There’s a reason that Clear History isn’t called “Delete History”: Using the feature will disassociate browsing data that Facebook collects from your specific account but it won’t be erased from Facebook’s servers completely, Baser said. Instead it’s just “de-identified,” which means it’s stored by Facebook but no longer tied to the user who created it.