I suspect the key difference here is that I'm not a Crossfitter, therefore don't run in the circles where I'd get hit with the hardcore evangelism. Which is almost always obnoxious, on any topic.

So I can dip in and out, take what's useful for me, ignore the rest, and nobody's going to be trying to burn me at the stake for eating a broad bean.

The major sticking point seems to be in the idea that by micromanaging macronutrients you can fine-tune how the body behaves.

Well, for me, being fairly stringent about getting enough protein (and for me, "enough" turns out to be a lot) and minimizing high GI food (except immediately after exercise) has turned out to make a quite drastic difference to how my body behaves.

(As I am proving right now, sitting here feeling like shit because lunch was a sandwich and a sugary thing grabbed on the run because I needed the calories and did not plan ahead. It happens.)

So I do buy that as a basic principle.

OTOH, I also suspect that the right macronutrient mix (and how important it is or isn't) is going to be very different for different people. For me, when I'm climbing, I need significant carbs not to falldowngoboom, and one of the many reasons I'm not purist paleo is that there is no conceivable way I could face eating that many sweet potatoes (and I like sweet potatoes). Also, I refuse to carry cold cooked sweet potatoes around with me.

So I make protein balls with brown rice syrup, and I'll usually grab some sushi and edamame or chicken curry with rice (or a steak and chips) afterwards, and my body seems to be just fine with that.

I feel like I'm seeing an awful lot of high-pressure rhetoric claiming that ancestral equals good and modern/agricultural equals evil in a way that mirrors conspiracy talk. It sets my teeth on edge.

Indeed. I'll stay here in the 21st century with the medications that keep me not dead, thanks very much.