[scarface74]

I think this was originally done when Marco Arment created Instapaper. He’s been trying to come up with a way to avoid passwords for years.

With Overcast - his podcast player, he also doesn’t require a username or password anymore if you’re just using the iOS apps. You can add a username and password to your account if you need to use the web client. But of course this is more secure. It’s piggybacking off the fact that you are logged into your Apple account (no, the Apple ID that is being used is not your actual email address, it’s a token)

https://marco.org/2018/04/27/overcast42