Proof of coverage can be important.

It used to be common for insurance companies to look carefully at your coverage record, and if you had any time during which you were not covered, they'd say stuff like "Oh, that horrible cancer you have? Yeah, we're not paying for it because it was a 'pre-existing condition' that you got during that weekend you had between two jobs six years ago." And the law let them do that.

Health care in the US is . . . the phrase "utterly broken" isn't strong enough. We need a good fifteen syllable German word for how fantastically fucked up it is.

Of course I'm trying to explain Anthem hanging onto data. Probably it was totally selfish ("we can send them spam") or sheer laziness.