Basically it's a story of a regular account got hacked and used for spamming. This must have happened a lot. But Facebook is so incompetent that it cannot ident

Basically it's a story of a regular account got hacked and used for spamming. This must have happened a lot. But Facebook is so incompetent that it cannot identify this very obvious pattern: 1. A legitimate account has long history of posting organic content. 2. The account email/password gets changed. 3. The account starts doing spamming. Seriously, how hard is it? How hard is it? If Facebook really care about the legitimate user behind the account, they can easily get this problem fixed. If I am wrong, please enlighten me why it is a problem difficult to solve.