This shit is outdated, it was written when Zoro hadn't even awakened conqueror's haki. He's a specialist in conqueror's haki now that we know he has a kingly ambition like Luffy
This, Oda likely wanted to keep CoC for Luffy then realized it will Hurt the Luffy/Zoro Dynamic and so rectified that in Wano.
Also yes their Conqueror haki is equal, the difference is bases on other state like physical strenght, Skill.
I think this arc Kizaru is going to get the smoker traitement,Luffy will troll him with his Advanced haki and Zoro will easily fight him.
Kizaru will realize he has been surpassed just like Smoker.