I agree with the author that in the short game not providing your own accounts is attractive. However in the long game it doesn't look so good. Unfortunately there are problems with using federated auth everywhere.

* It's a single place for a compromise to occur - the devastation of a serious identity provider hack completely upends the security of huge swaths of the internet in a single shot

* Breaks in fedauth protocols and implementations, similarly, presents a large auth crisis for the entire Web

* It's a single place for legal or extralegal pressure for governments to access services and data on behalf of everyone

* It creates market friction. If federated login had been around in large numbers when Myspace was the big social platform we'd still be using Myspace for the sheer reason we need it to vouch for our identity. It makes the big fedauth players 'too important to fail'

One should consider options carefully and determine whether a good user experience can be offered without further centralizing the Web.