Facebook could not afford not to as they would lose a huge amount of users. Apple is just doing to them what FB does to people: Accept these terms, be tracked everywhere, or miss out on all the people providing us free content on our platform. Many people accept that because they don't want to be unable to communicate or view things in their garden. That is leveraging their huge scope to push less favorable terms.

So FB has Apple with some leverage over them saying accept this or else. FB is in a weak position because it would be hard to tell your users hey leave Apple because they won't let us take all your data without permission. I don't feel for them at all.