As a company, wouldn't you want to diversify your properties? What good would it be to have Cedar Point and Kings Island be overly similar? They are not terribly far from one another, so visiting both isn't an unfeasible task for those in their respective markets. Look at Delirium and Max Air, having ridden Delirium, I have no real desire to go to CP for Max Air. Their other flat rides that Kings Island doesn't have are attractive to me though.
Why would Cedar Fair want to purposefully hinder or in some way limit one of it's own parks? Each park is unique and requires different management and additions. A small subset of guests may be clamoring for more record breaking coasters but they are likely the minority in the whole populous that is Kings Island's guests.