I heard that a thousand times in the last 20 years. Mostly because people don't understand how the Bosch K-Jetronic works and therefore were overchallenged when something went wrong (what seldom happened) or they were trying to get power out of them hillbilly-style.

The K- and KE-Jetronic (KE was available also as N/A with 90 hp) CVH units were VERY reliable, fuel consumption and power output was better than in EFI cars, especially N/A XR3i. Reconditioning of the mechanical parts can be done quite easily, as far as you know what you're doing. Bosch offers ALL parts and all type of work for the K(E) via "Bosch Automotive Traidition". Only tricky part could be the Ford ESC-II module, but these usually don't cause problems.
90s Ford EFI... new parts are rare or not available and when you face an electronic problem you're totally lost today with these units unless you know someone who kept all of the old diagnostic tools etc.

And... I don't understand why Porsche, Ferrari, Audi, VW, BMW, Mercedes-Benz, Ford and many more used the K-Jetronic for ages when it was shit???