It is not entirely true that 10 years of past data is enough for fb to draw conclusions on a person. In fact fb is trying more to make people share. You can also try 'tools that fudge info' to confuse fb. If done cleverly, this is a major tool to put fb off the scent.
Also, Quitting fb for mental sanity is a worthwhile reason if not privacy
I quit Facebook around 2011. One funny/shocking thing that happened is I got email notifications even after 14 day grace period. I had to go and click the unsubscribe link manually to stop that even though I don't have a valid fb account at this point of time. Not sure, if it is happening still.
Another one - I created a dev account some time back with dummy email Id, but gave my mobile number of deleted account. Voila ! Facebook was suggesting my old contacts. Though this was suggested as expected by scanning the contacts of suggested members, I find this creepy enough.
I'm a happy and relaxed person for six years now, and as with all other things you will get used to life without Facebook. Deleting fb account is not like jumping a ring of fire as your social circle might suggest.