Is anybody saying that? I think the main problem is that it's a Google site, not just any site, and not just a "site" either: it's endeavouring to be a social network and a platform. I'm not entirely sure what a platform is, by the way, but think it's the foundation on which other webdevs can build things. If so, it will set some initial standards or expectations which everybody else will need to adhere to if they want their apps to work with it. And something that Google's executive chairman Schmidt said the other day: they think the internet lacks "an accurate identity service". In the context of what he was saying, it seems that maybe Google+ is their way of building that. The transcript is in an Andy Carvin Google+ post if you're interested:
https://plus.google.com/117378076401635777570/posts/CjM2MPKo... Google isn't the entire internet, obviously, but it does have a big influence over what happens elsewhere.