The thing is many of these rankings put a great deal of emphasis on research program quality and impact. For IITs at least, the research programs are nowhere a

The thing is many of these rankings put a great deal of emphasis on research program quality and impact. For IITs at least, the research programs are nowhere as good as many top western universities. I studied undergrad in an IIT faculty that's considered the top in its field in India by reputation of the professors and I worked on two research projects with PhD candidates there. I also spent one summer working on a research project at KTH in Sweden. I must say the experience in terms of research quality, capabilities of the PhD students, facilities, support systems etc was night and day. Due to this in the IITs, the top undergrads leave the country to pursue post-grad and the folks left behind are often the ones who didn't get admits with financial support outside. Very often I observed the undergrad students assisting with the research understood things better than the PhD candidates themselves and all these makes a difference in the research quality and impact. Now, if you rank university programs in terms of % change in life circumstances, IITs will very likely come at the very top. Because the entry is entirely meritocratic with minimal reservations and even reservations are held to academic standards - seats go vacant rather than being filled with less qualified students - a lot of students from poor families get boosted solidly into upper middle class with an IIT education including many of my own batch mates.