I'm the author of that post, can't recollect many exits from web-based companies in India to companies from outside in India. You could, I guess, point at sosasta.com (acquired by Groupon), but the deal flow certainly is not there.
With that explanation, you are implying that your post is observational only. IE, you could drop the "why" from the title and gain accuracy in describing the post.
In order for either of these points (your two points seem to have been joined here) to be interesting for answering the why you need to look at Indian companies that would have been bought in the US but weren't (presumably) because they were Indian. Whatever the reason, if it is endemic, could be a why.
As is, you kind of end just observing that YC like investors or YC like startups don't often exist (or maybe succeed) in India but aren't really commenting on why.
