The Spy Classic addon has been used for numerous nefarious purposes by others, and it’s extremely widespread. Gank squads have been using it en mass in order to locate lowbies from literally hundreds of yards away when they otherwise would never have been noticed. City raids have been completely stopped in their tracks since warlocks wanting to try and sneak summon people into the city in order to get past the chokepoint can’t do that anymore. Any possibility of using the element of surprise in world PvP has been completely choked out, as anyone with the addon will know if you come even remotely close to them, making Stealth ineffective both to sneak up on enemies or to sneak away.
I know some of you are going to say “Addons did this back in Vanilla too, so it shouldn’t be broken”. Addons also did the same thing ClassicLFG did back in Vanilla, but that didn’t stop that addon from being broken here in Classic, and the combat log addons back then were far less widespread than Spy is now.
If ClassicLFG, an addon that not many people used and didn’t behave anywhere near any of the LFG tools that Retail has seen in its history got broken, then Spy Classic should be broken as well.