Yes, it's because it's the one point for which I've seen no evidence at all. I don't actually agree with your thread title because I don't think any of it is bollocks; I think all the different viewpoints, which all can be scientifically proven, need to come together and make a whole. They are jigsaw pieces, rather than arguments which disprove each other.
Many people will think that one form of dieting works for them, say, low carb, but they might not realise that by going low carb, they started to eat less calories. So they think low carb wors, but what they actually did was more CICO. Or conversly, I'm sure that many people have tried to lower their calories, and done it via giving up bread and potatoes and chocolate, so they think CICO works, but what their body has responded to is the drop in carbs.
There's a lot of 'you are wrong and I am right', and there's a lot of 'it worked for me, so it works'. Different things will work in different measure for different people. Weight loss hormones are a s different from one person to another as height or size of nose; we are not all the same, by far. And yet we are given one set of rules, and it doesn't work for so many of us, because we rely on that set of rules as the full story, and if it doesn't work for us, we self criticise.
It's a bigger picture, there are more options, and sometimes it's necessary to experiment before you find a way that works for you, your body, your lifestyle, your personality.
It's not 'I'm right and you're wrong', as your thread title seems to suggest. Cutting calories and being more active works for many people, even if there's a high failure rate. It might not be working for the reasons people think it's working, but, for those who have success, who cares?