As I understand it, most of our carbs come from grains. Paleo is a low-carb/no-carb diet because of the elimination of grains (high-glycemic carbs). There are still some carbs in paleo, but they should be low-glycemic carbs such as sweet potatoes.
Maybe I don't understand what keto is; I thought it was eliminating/reducing carb intake so your body burns fat instead.