Originally Posted by
IAN-UK
It's not exactly nonsense. Controlling access to airports' airside areas is considered necessary where meeters/greeters/sender-offers, as well as the curious and the nefarious might otherwise overwhelm facilities. In India there is also a very strong security imperative to implement these controls: it's a country where memories of 2008's multi-day terrorist assault on Mumbai remain close to the surface.
Nor is India unique in having extra checks, and not just in airports. Visitors to IST will be abundantly aware of a stringent security check to enter the airport, then a further one to get airside. You will often see metal detecting scanners at hotel entrances.
Those countries consider it prudent given their domestic security situation and in the case of India - as
IAN-UK indicates - the terrorist attack in Mumbai remains a warning to the authorities of what can happen if you relax your guard. That threat has not gone away.