Addons have been in WoW since the beginning. We used addons in vanilla. Even boss mods existed by 1.12. Quest/leveling guides also existed, you just had to alt-tab to read the next step and off you went.
It’s not easy breaking addons. A lot of the addons many of us might like to see broken would also in the process break addons we don’t mind. Breaking LFG addons might brake roleplaying addons that rely on similar communication methods to sync and share, say, character profiles. Get what I’m saying?
This would require–yes, REQUIRE–a major UI update. The stock vanilla UI is utter garbage. Even back in vanilla we all knew this and used addons to provide baseline functionality the stock UI lacked until like MoP. I don’t oppose the idea of Blizzard curating a selection of approved addons, but I don’t see them putting in the extra work and I don’t think most people actually feel strongly about this.
Addons existed and were used in vanilla. And if we wanted a true, authentic experience we wouldn’t be excited for a 1.12 private server model rollout that leaves most of the game in a nerfed state. Let’s be honest.