The quality of your peers is an important feature of any educational system (if not the most important) -- by that measure alone the top institutes in India are excellent. The top researchers/professors at those institutes are also a product of the same institutes, and the same selection process, so the top institutes are generally of a high standard (in terms of workload, choice of topics, teaching quality, etc.). Although, here, admittedly the draw of industry and universities abroad has a large effect and the teachers are not the top 0.01% of their age group in the same way as student are.