The idea of fasting really isn't that crazy. People have been doing it for 10000 years. The idea of 6 small meals where your insulin never goes down is what is crazy. We weren't designed to work like that.
And fasting can be a life time thing - once you are at your goal weight, you can easily incorporate it into your life - whether by 16:8 or every other day etc. You can still work out. No you aren't to build big muscles in the gym while doing it, but normal running 3-5 miles, no big deal.
But for people that are 50-150 lbs over weight it can change their lives - for years everyone has been told to just eat less calories and move more - we have 30-40 years now of evidence that for the majority of the population, that it doesn't work. Reduce calories, you reduce your metabolic rate, go back to eating normally, gain it all back. Fasting may not be for everyone, but for those that can be helped by it, its great.
Plus there are other benefits as well, Autophagy (which a guy won the nobel prize in medicine in 2016 for), mental clarity, euphoria and plus its free.