Discord is primarily "gamer" focused, so macros are often pointed out as a means of cheating or otherwise gaining unfair advantage. AutoHotkey (https://www.autohotkey.com/) could be used to chain a bunch of actions in a game together and perform some sort of difficult action with minimal effort, so that's discouraged.

But the rule is very odd. Most "gaming" focused mice/keyboards have software and buttons dedicated to performing macro functions, and they're present on major brands like Razer and Logitech equipment.