I don't think anybody's claimed that it reverses ageing, and if they have I think they would have clarified that they did mean 'slows' the ageing process. And there's no doubt that caloric restriction and IF both slow ageing relative to a normal caloric intake. I don't have the paper on me atm, but IIRC it was 30% longer lifespan in mice. Now whether you want to say ageing is slowed or that lifespan is increased, and I'm not denying that there's a legitimate difference, but either way caloric restriction is completely legitimate for both, and to the extent you said it's useless, I don't think that's fair at all.
For anybody interested, the mTor pathway is really interesting in this regard, and in general the effects of AMPK on cellular metabolism. TLDR is that in the modern world most people never activate these pathways (since we're always in a fed state). Ostensibly there will be some breakthroughs when we finally learn why these starvation pathways are so beneficial. Inflammation seems a decent guess - eating increases it, and fasting decreases it, as a general rule.
