I'm pretty sure it's more "increase the size of the market" than it is "give it more data". The latter is just a side effect of the former.

By getting more people online, they have more connected eyeballs for which advertising can be sold. It must be hard to sell adverts to Indian companies today when the target markets of those advertisers are not online (or not online enough).

It is fundamentally about growing the size of the pie, and everyone benefits from that (though yes, Google and other big internet companies perhaps benefit most).