The help page about deactivating or deleting (they are two separate actions) makes it quite clear that your data will be gone, not merely rendered inaccessible, when you delete: https://www.facebook.com/help/250563911970368
That page uses the phrase "permanently delete[d]" multiple times, says there's "no option for recovery," and calls out some information they do keep because it's not actually part of your count, implying that the rest is not kept.
Did you even read the comment you replied to?
Years ago they did not delete accounts. They would deactivate it and never delete the data. They do now (apparently), but in the past they were very openly not deleting anything.
Yes, I read it. I took it as meaning that they either read something else which was unclear, or just deactivated the account, or misremember what Facebook said at the time.
Do we know that Facebook actually deletes accounts now?
So maybe the author of this post removed his account at an earlier period when Facebook didn't make such an honest claim. In that case the title should be "Facebook used to lie."