From a broad observation of keto diets, It appears the main benefit may be from what foods are reduced or avoided than any ketosis effect. MCTs and other diets are like adding gas to a hybrid without regard for the fuel level in the tank. Only so much MCTs and other fats can be used. But, removing the carbs, especially bad carbs and being focused on healthy eating rather than the trash eating common to many diets can be a big benefit. The human body was never designed for the sugar and carb consumption levels common to many diets.

It would be interesting to see a compilation of the good carbs. Does the glycemic index (GI) of carbs have a direct relationship to good or bad carbs ?

Beans are our common carb. They have a GI in the 30s. A GI below 55 is good. Below 40 is great.