Just saw that Andre Durand blogged this a couple of weeks ago:

Perhaps one of the most powerful concepts of OpenID is the fact that it gives the user a visible ‘handle’ (identifier) that is used and handed out at relying party websites.

It could, quite possibly, end up becoming one of the most important concepts OpenID and LID introduced.

You know how sometimes it’s the little things that get dismissed, overlooked or discounted, when in fact they end up being really important? The visible identifier, in this case, is that little thing.

Little nitpick in the interest of historical accuracy (and self-interest…): “that LID introduced” (OpenID 0.x/1.x came so many months later)

But of course I fully agree that having URLs as portable identifiers for people was and is a really good idea, although in hindsight, a very very obvious one. Adding meta-data discovery to it then made it viable as a foundation for building greater things on top. Which is why the thriving OpenID community became possible.