@desa:
He probably think that's what happened to Monet when she couldn't move.
yea, kinda.
We don't know much about CoC. We just recently saw it "clashing" Don C vs Luffy. As armaments, it prolly has a few different uses (coA has hardening and so on). We simply can't be sitting here talking about something that wasn't explained fully but to me, CoC isn't that big of a deal. But you still need a strong spirit to use it properly andyou need training (as in, using it on specific targets and not everyone around).
All i can think of are all the main heads in the new world having it. You can't expect for it to have been popular in the blue seas or the first half of grand line. New world is where all the strong people go. From now on we should expect seeing alot of haki users and strong fruits running around.
1 in a million isn't that low also. We have around 7 Bil people today. Imagine that OP world has 1 billion only: thats 1000 CoC users. From those, imaginne u knowing only around 20 who can use it . I don't even think we gonna have 20 people having it on OP.
But i do immagine sanji, zoro, garp, dragon, BB, kaidou, BigMom and around 5 other chars having it till the series are over.