I'm not sure it matters. You still have to agree to the policy first. Whether you have an FB account at the moment might change for you in the future right? So FB couldn't be handling all those cases as well. This is a strategic move I think will cover all users.

I think everybody has a (shadow) FB account. FB collects your data and connects it to other data even if you never registered.

How, apart from whatsapp, would it collect your data? The only social account(s) I have are on reddit.