It's because quite a few Indians are super racist. Especially against anyone (even other Indians) that are dark-skinned.
It's no surprise that bleaching cream is incredibly popular in India, and that all the Bollywood actors are incredibly fair-skinned. Hell, usually their music video dancers, cheerleaders at IPL games, etc..., are all just white people. Historically the higher castes also consisted of fair-skinned Indians.
Doesn't surprise me that Indians would object to 'questionable' (ie. African or Black) neighbours...
It's the particular distaste for Africans that I don't understand. All foreigners face a degree of racism, but Africans seem to get it the worst. Women tend to be the most racist, morality police and spurned vixen depending on the situation. If an African woman wears shorts in her housing society it's a danger to good morals. And if an Indian woman tries to pick me up but I don't feel like dumping my (Mozambican) girlfriend right there, somehow the black girl is the problem.
Passive aggressive mob justice doesn't sound so hot when the victims are members of our tribe, does it?
(Background for westerners: Indians don't really like Africans much, particularly in the abstract. I have no idea why. Various non-Nigerian Africans blame it on the fact that Nigerians are all criminals and give Africans a bad name.)