[carl8]

> If I was Google I would be providing ... a loose social network that encouraged links to other sites (perhaps similar to HN on a larger scale) that would be easy for third-parties to integrate.

They did. It was called OpenSocial, which originally released in late 2007, and was implemented by MySpace and others to compete against the Facebook platform (also released in 2007). I remember when I first looked at its complex XML documentation, that it was much easier just to use the Facebook API.

https://en.wikipedia.org/wiki/OpenSocial

[nl]

OpenSocial was a standard for "widget" which could be hosted on a site. I don't think it was ever used on Plus, but it was available on iGoogle.

That was more for games than for the type of links the OP was talking about though.

OTOH Google did a lot of work around things like PubSubHubbub to get cross site links working.

[swivelmaster]

OpenSocial was great in theory, but in practice it was awful. At launch, it had a fraction of the features of the FB platform, was much more complicated to build for, and its behavior was not actually consistent across all the social networks that implemented it. I joined a startup that was building for both FB and OpenSocial and as soon as we had a successful Facebook game we ditched all thirty-something OpenSocial widgets.