Thread:Andrewds1021/@comment-47475593-20201127004334/@comment-9605025-20201127053144

As I said, you can't edit it because that page hasn't been whitelisted. In order for admins to be able to edit pages in the MediaWiki namespace (a.k.a. system messages), those pages have to be whitelisted by Fandom. The reason is that the pages in that namespace are used for controlling a variety of both frontend and backend behaviors of the wiki. In order to ensure a similar appearance between different wikis (required for good branding and profitability), Fandom wants to limit the customizations that wikis can make. Additionally, some system messages could be abused for nefarious purposes. I don't know all of the details myself since I was a relatively new user at the time. However, there was an incident years ago where a user used a system message as part of a major account hacking attempt. The managed to steal tons of user passwords by creating a fake login page. They even managed to steal the password to a staff account and then went on a rampage of mass vandalism, retaliations blocks, account closures, and deleting large and popular wikis. Fandom was able to stop them but it took days or even weeks to fully recover from the attack. In response, Fandom made changes moving forwards. The locking of system messages was one of those changes.