To give more context, last week, the team behind TurboHUD released a version of this overlay tool/mod for Diablo 4. TurboHUD helps keeping track of your progression, your performance, and allows you to add quality-of-life improvements to the user interface. This mod was also available for Diablo 3, and a lot of gamers were using it.
A UX and progress tracker is getting people banned. How fragile is Blizzard? They're probably afraid this will somehow give people an unfair advantage for those leaderboards that won't exist for at least 6 more months.
Jaysyn