It’s a different team, with a different skillset, that would be responsible for that. Big companies can focus on more than one thing at a time.

They ban like 1.7B account per quarter ignoring those blocked at registration. Isn't that focus?

Subjectively too I also see so much less bot activity on Facebook than I do on any other social media.

I think that large tech companies giving a snapshot of what cool or interesting things they do is great but if there are bigger problems that don’t seem to have that kind of focus it just feels like a marketing / recruiting post (which isn’t that bad). But, the problem would be if they made public antispam systems they can’t give that to spammers which presents as a catch22. Also if you have humans in the loop to evade a spam system it is basically impossible .

At the scale of FB, handling fraud is a non-trivial effort. At any given time there are probably thousands of somewhat well funded fraud teams looking to bypass whatever shiny new countermeasure FB adds to their site.

There is a lot of money to be made from defrauding FB users. This monetary incentive results in criminals investing tons of effort into bypassing anti-fraud stuff. It is a non-stop effort of incremental moves on both parties that will carry on for as long as FB users remain a juicy target.

Somehow I knew it was going to be a bit.ly link before opening the image