Perhaps we need an address clearance service. People used to be able to use the post office for this... "Notify everyone who mails me that my address has changed." We need to have this for every way we connect. And people need to own their data.
Max Niederhofer blog: Why are contacts still such a mess, 2018-Nov-4
When I think of building contacts consumer software, I think it should be fully decentralized. Everyone should have their own record and permission who gets to see what (name, email, phone number, postal address in increasing level of sensitivity). An app sounds like the right way to do that.
Then scale it via OAuth to other apps: if you’re in contact with a person in Gmail, call them on the phone, meet them in person as tracked by calendar, prompt a data access permission flow.
And don’t even think about replacing the address book. Just build it alongside it, without touching the old world.
The nice thing about contacts, of course, is that you can grow virally (carefully, without spamming the world).
For some reason every company we have ever seen try to build something like this has failed. I’m not sure why.
If you are thinking about taking a crack at the problem, talk to the folks who did Bump, Brewster, Plaxo, who are now doing FullContact. I’m sure there’s a wealth of knowledge there.