I find that the protection level descriptions are confusing: "Allow all users" / "Block new and unregistered users" / "Administrators only".
The first option allows, the second option blocks, the third option ???.
Better: "Anyone can edit" / "Only established users can edit" / "Only administrators can edit".
Version: unspecified
Severity: enhancement
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=16791
https://bugzilla.wikimedia.org/show_bug.cgi?id=44497
https://bugzilla.wikimedia.org/show_bug.cgi?id=43283