Imo, it comes out of having to sell the partition of India and Pakistan as 'natural religious divides', and then selling hindivatu nationalism as the 'deep spiritual ancestry' of a country that was historically multiple petty kingdoms with a myriad of faith traditions, with one of the most historically overwhelming not being a unified Hinduism, with is a faith practice that attempts to amalgamate myriad traditions into a singular whole that reifies a singular ruling elite and was typically practiced by the upper caste, but Buddhism, which came as a response to Hindu elitism or local animistic/ancestral faith practices and of course areas of Islam sprinkled throughout.
That and it created an anti-colonial 'spiritual alternative' to baby boomers who understood that capitalism was eating their lives but still had communist brain-worms, or baby boomers who were extremely successful under capitalism but had rejected Abrahamic faiths as being too 'impure' (as they actually understood what was being talked about, nothing helps faith like not understanding what the fuck is actually happening). Basically, people who don't actually understand what karma actually is.