[crazygringo]

So is the article just plain wrong then?

Can an app given full-disk permissions not access data in other user folders other than the user who started it?

This is why I'm so confused.

[brigade]

To an extent neither are wrong - full disk access doesn't directly bypass the live filesystem's Unix permissions. But it does explicitly grant full access to Time Machine backup images regardless of admin/superuser privileges, including the ability to create new up-to-date snapshots, which is equivalent to full read-only access ignoring Unix permissions (on a short time delay.)