> And yes, I intend to use FB in 'read-only' mode from now on.
If you visit a profile, view a video, open a group or message it's all recorded. I'm betting that they can even tell the probability you read an ad just by seeing if you stop scrolling on it and then start scrolling again.
Some actions are completely out of your control, though. Other people can still tag you (on pictures, locations, etc.), even if you hide it from your timeline. If there's an option to prevent people from tagging you, I haven't found it.
(for sure, the process is only a "soft-delete")