It seems to me to be spurious logic to say that low-fat eating has been the cause of the obesity crisis. I'd say the diet industry has risen in response to the obesity crisis rather than the other way around. The problem isn't that everyone's been on a diet but everyone's been getting fatter, it's that people haven't been controlling their eating, they've been eating too much bad food and getting fatter, and the diet industry is inevitable background noise.
I do think eating low-fat is poor advice, but not because it doesn't work, just because it's very difficult to stick to. It also (like LCHF, I guess) only represents half of the picture: eating low-fat by no stretch of the imagination means you can eat as much as you like, and since those awful processed low-fat "alternatives" which were peddled so much in the 90s gave you that dissatisfied, empty feeling, I think it's very easy to gorge yourself on "low-fat foods" and still not feel satisfied, which is really counter-intuitive.
I think the real problem is, and has been for decades, that people simply don't want to admit that they can't eat huge portions of calorific food and not be fat. Lots of people want to lose weight enough to stick to a diet (any diet) for a bit (hence the diet industry and eating fas), but very few manage to make a lifestyle out of it. It does seem like LCHF is a more palatable 'lifestyle' to people, which is probably why it's having such a moment right now, although personally I couldn't stick to it myself.