Here it is in a nutshell: No grains nor legumes; minimize fructose; minimize PUFAs; emphasize MUFAs and saturated fats, especially short- and medium- chain triglycerides; aim for 20% carbs, 65% fats, 15% protein (by caloric value); fiber is good (because your gut bacteria convert a lot of it to SCTs and MCTs).
The 20/65/15 ratio may need to change depending on how active your are and how damaged your metabolism is.
Butter contains a fair amount of butyric acid (a short-chain triglycerides), so it would make sense to add it to your diet. I prefer coconut oil because it is about 50% MCTs and typically doesn't require refrigeration. I eat a lot of it, and it tends to fire me up like a rocket.
And, yes, I've lost approximately a shit-ton of weight on a Paleo diet.
I remember hearing a story of a professor who would throw asbestos into the air during lecture saying they had no evidence it was a health hazard, which was true at the time.
Yes, the health/nutrition industry often has uncertainties and disinformation and it may well turn out harmless, but why gamble with your health?