Not true (I believe). You can deactivate your account - in which case it’s all there waiting for you to come to your senses. Or, you can permanently delete your account and all your stuff is gone (from you, at least) forever.
At least that was my understanding a couple of years ago when I decided I had had enough of watching my niece and her husband hold arguments on FB. They’re a great couple, but I realized that I was wasting way too much of my time on it,so I wrote a little opus and went completely away.
Haven’t missed it for one solitary second since then.
As the old commercial (for what, I can’t remember and am too lazy to look it up right now) said, ‘try it, you’ll like it.’
I'm not going to try looking it up either, but I seem to remember it was Alka-Seltzer, and the "try it, you'll like it" line was a reference to an entree dish that occasioned the need for a remedy, not the remedy itself.
(Alka-Seltzer ad campaigns could support an undead thread all on their own.)
If you go back to facebook and sign in all your stuff will be there, FB will ask you whether you want it back