[Matheus28]

Why? Some web apps might want to present a different interface if you’re in landscape.

[shimman]

You don't need an angle for that. That is highly invasive and can be used to target unique individuals. Why not default to a pro-human oriented mindset rather than pro-corporation?

[hparadiz]

It's for games that rely on the tilt.

[wtallis]

That's much more reliably conveyed by looking at the viewport dimensions.