I think many would argue that thinking Facebook doesn't have your phone number is either massively ignorant or stupid. After all, it only takes one person you know signing up and allowing access to contacts.
That said, I am considerably less concerned about Facebook having my phone number versus Facebook being able to mine all my conversations to create a pretty complete profile of who I am and what I do.
I have never uploaded my phonebook to WhatsApp durring the short period I used it nor did I give my number to Facebook (either by entering it into my profile or by answering the nags to enable 2FA when I used to use the site.) It was not included in the recent leak (which doesn't mean they don't have it.)
That said, I am considerably less concerned about Facebook having my phone number versus Facebook being able to mine all my conversations to create a pretty complete profile of who I am and what I do.