[scarface74]

An app developer being able to uniquely identify a device across applications has been considered a privacy violation for well over a decade. Even Microsoft in the Windows CE days made it hard for an app to uniquely identify a device.

[altfredd]

The idea itself isn't bad, but Google's implementation of it is terrible. Good actors are forced to show security prompts, that literally scream "this application is malware!!". Bad actors enjoy ability to share MAC/IMEI/whatever with each other and skip whole "prompt for irrelevant permission" nonsense. They don't even particularly care about reading hardware addresses — why bother, when you can embed something like fingerprint.js and automatically identify every single device in existence!

If Google does not improve their P2P networking APIs, everyone may end up eventually integrating some Chinese spyware library, because it is the only approach that does not suck (and there is apparently no penalty for doing so).