FB runs bots over the platform to detect these accounts. Since they have everyone's contact list, they can just check your friends list and see if you appear in their contact lists. If not, they will lock you out and require you to send a photo of your ID.

And even if they have not yet, they can at any time and all of your games and hardware get locked which is permitted in their ToS. Why would you want to take this risk when the alternative platforms do not have real identity rules.

Hmm, I can understand getting banned for having a side account. But GP claims they fully deleted their account, and created a new one. What is Facebook gonna do, punish them for no longer having a FB account? What if I happened to have deleted my FB account a year ago and want to play Oculus now?

For people who don't care about the account they made a decade ago and no longer use, this seems like a reasonable and probably safe approach.

I was asked by Facebook to create a second account and hand the details over to their developers in order for them to have access to a platform we're developing for some validation regarding our use of OAuth, it's probably also against their TOS, yet had I not done that they would've locked us and our users of OAuth...