The credit card insurance isn't very comprehensive.
Credit cards usually offer collision and liabilty though. Usually it'll provide secondary insurance, meaning you pay the rental car company and then the credit card pays you which certainly damn annoying if you happen to make use of it, but considering rental car insurance can run you like 50% of your base rental, it might be worthwhile.
Obviously, I am not an expert, and people should always carefully read the terms and conditions of their credit card coverage!
But if you're gonna do that, be prepared to crawl all over the car surface for half an hour prior to taking it out of the lot and after bringing it in, documenting every scratch and dent and thumbprint, for as sure as sun rises, if you don't buy comprehensive from them, the car company is try to stick you with some kind of bogus repair charge!