[allover]

Well GPP is just saying that 'calorie restriction' is not proven to 'help you live a longer life', irrespective of the IF context.

As for IF, as you say, it is basically not proven to do anything (no 'phenomenon' at all). Simplest and most logical reason for success is because it helps people stick to their diet, by arbitrarily restricting the window of eating.

Opinion I read on r/leangains is that some people find it easier to e.g. just eat two 600-800 calorie meals within their IF window, rather than sticking to a diet that involves 3-4 smaller ~300-400 calorie meals, spread out through the day, none of which feel 'satisfying'.