[numair]

On the web? There's this great new innovation called cookies that allow for site-based identity!

As for cross-platform and token changes -- well, you can't deal with those situations when you're implementing something that's actually anonymous. You're going to have to implement some sort of persistent identity. At that point, you might as well offer a multitude of options, of which Facebook would be one.

This login creates an unnecessary point of friction for all anonymous applications. Just use an existing token (cookie, device token, etc), allow your user to immediately begin using your app (that's what they expect anyhow), and "ease your user in" to a point of giving you identifying information if you need it.

[Reedx]

How would cookies solve it considering that they are temporary?

Even if the cookie expiration was set for 100 years, it's going to disappear the moment someone switches their browser, gets a new computer, clears their cookies, etc.

[placeybordeaux]

Not to mention that this does nothing for having the same login for phone and browser.

[untog]

you can't deal with those situations when you're implementing something that's actually anonymous

True, but this login isn't "actually anonymous" - but I can't think of a better term so I don't blame Facebook for using the one they did. It's effectively a global ID with no data attached to it.

[thinkling]

Pseudonymous is the term you're looking for, I think. An identity that's not tied to your real-world identity.

[jcampbell1]

Let's say I want to create a service like Instapaper. I don't care about the person's facebook info, but I'd like to optionally give them a way to login with a simple button press without having to create another username and password.

This seems like a reasonable solution.

> Just use an existing token (cookie, device token)

That won't work because the mobile and web account have to be connected.