It isn't though, at least not in the same way. It's not as if apps can't generate unique identifiers like a UUID. What's important for fingerprinting isn't that it's unique but that it's stable across different apps which this wouldn't be. You could maybe try to eek out a bit of information with "value is greater than" but it would be hard to orchestrate because you can't guarantee that all apps will be first used around the same time.