IMO there is little value in actually quitting facebook.

If you aren't using their apps and block their embeds on third-party sites it just sits there and allows you to be what our parents described as a global phone book.

I deleted everything I uploaded, unfollowed everyone, locked it down and made a backup. Most of their indeed very creepy practices are optional.

edit: this is also probably a good learning for other services: have a working non obstrusive mode to retain almost-off users.