I'm struggling to find a point in this suggestion. This would require a way for staff to be on track of people who have more than X disorders, meaning they'd need to have a system in-game or a list somewhere else to register and check people. Besides all that, this'd also bring yet another thing to enforce and moderate, which is extremely difficult, since they already have many things to keep track of.I think they are specifically only applying this situation to people who want more than 4 disorders on one character, not if you want a disorder in the first place.
As Yonio previously mentioned, people can always report anyone who is making things too fiction-ey or unrealistic, but who's going to judge whether a type of roleplay is unrealistic or not is the staff team.
And on the same note, my point of "You shouldn't be limited by an authorization system and extensive guidelines that only limit your creativity" still stands, and I believe this proposed system would only increase that quite well.