The SCD and GAPS diets are based predominantly around cooked animal foods. The results from these diets speak for themselves
Grains and legumes contains anti-nutrients such as lectins and phytic acid that can be problematic for SOME when attempting to heal digestive problems. Some of us then also have problems with starches due to fermentation/blood Sugar issues.
One example of a Crohn's patient who managed to put it into remission on an all meat and fat diet.
At the end of the day, the human body can seemingly thrive on any type of diet so one has to work out what works for them. Any 'diet' should only be used as a template. Ultimately you'll have to carry out your own n=1 experiments with food.
Just don't be so quick to dismess the therapeutic effects a high meat and fat diet can have.