Title seems misleading. Per the article it seems they demand email confirmation, but merely offer to access your email for you in order to accomplish that.
(This is not a defense of Facebook's actions here)
(This is not a defense of Facebook's actions here)
It's definitely a dark pattern though. And Facebook rarely seems content to only use data for the purpose they advertise when asking for it. For instance, there was an article recently that proved they were using phone numbers collected for 2FA to do ad-targeting as well.