Can high octane harm engine?

I'm not even talking about the racing gasoline. I'm talking about putting 93 oct gas in a Mazda. Seems there are some people in the mazda3 forum that thinks the super unleaded gas is screwing up the engine because Mazda recommends 87 oct gas. It just doesn't sound right to me but just in case, I've been running on 89 oct. Somebody with more knowledge on this topic please enlighten me.... Higher octane = less chances of detonation but harder to ignite?