I often hear people say that the hardest part is the prep, mainly getting rid of the imperfections. And as someone who has a buffer, I’m no stranger to spending many many hours doing paint correction (mainly from back when I had my black 98 Corvette!) But certainly one could simply apply a ceramic coating without doing any paint correction, it would be no different than applying any type of wax or sealant to an uncorrected finish, and people do that all the time. Certainly the results will not be the same and the coating won’t last as long but the time you save could be transferred over to having more time reapplying another ceramic coating every year or two.
I don’t think too many people would see the coating last 7-10 years anyway. Certainly not a car exposed to the elements often. And the hydrophobic nature of the coating would definitely be drastically depleted long before the 7 year mark.