"Any client had a full list of online players. A compromised client could teleport to each one and kill then rapidly."
I read this as "could teleport each one and kill them rapidly", so my bad. I did not go back and verify the exact phrasing again as you were already dismissive of any and all input, criticism and pleas with a "what we say goes" attitude in regards to mods. Yes, what you say goes, but at least take into consideration the people who supported your game during 10 years and kept it fresh with new things for the playerbase to enjoy while the core game matured.
Oh, the question above: it broke every single mod out there needing a fully qualified list of people. Examples are everywhere around the mod scene, smaller and large. I have a mod that allows vehicle claiming with permissions management. When somebody wants another to be able to enter they get a context menu to add them. Another mod is an economy mod allowing people to wire each other money via ATM and here i need an instance because i need to get first and last name instead of usernames, as it is in an RP environment. Also wiring money to somebod 10 tiles away is not really sensible. It is an "across the map" feature.