I agree with you, on paper. USB C should, by its design, have more port related failures. No argument with that.I wouldn't dispute your own first-hand experience. And I don't know where you bought your Lightning cables from. I've been using mine for years - but bought well-made ones.
As for the charging ports on Apple devices themselves, I believe most Apple Service providers or technicians can attest that the failure rate for USB-C ports (such as on Apple notebooks) is higher than the failure rate of Lightning ports on iPhones.
A broken cable is a 20$ replacement. A charging port on a phone however means (meant, before the advent of MagSafe/Qi charging) an unusable device worth hundreds of dollars - with your data on it.
But, cable failure rates are still relevant. I almost exclusively purchased Anker cables from Amazon and Walmart. Otherwise I got Apple cables direct. I suspect the differences in experiences come from two different but reasonable methods of using the device. If you use it frequently while plugged in the location and size of the plug promotes pressure being applied to the cable plug interface.
This isn’t a ‘stop doing that’ situation. It’s a design flaw. The product should be made such that it’s handled in a predictable way, and issues like this should be predicted and solved during development. The easiest solution is to allow the phone to be used upside down. Since that isn’t an option the weight of the phone will be balanced on the cable and the stress will be applied to the first point of weakness, the cable plug interface. When holding the phone in landscape the cable will be bent 180 to be moved out of the way of your palm. Not all apps allow landscape in either direction so one handed grips are not a universal solution.