Some differences:

AFAIK Apple will never lock me out of my App Store purchases and demand to see my passport

Microsoft won't take away the Xbox games I purchased if I use a pseudonym on LinkedIn or post Hacktoberfest spam on github

Steam won't ban me if I have separate accounts for work and personal use

etc

If having a Facebook account was less onerous and didn't come with as much overhead (for example, FB has banned people for making an account and not using the social features) I think people would be less up in arms