▲ ▼ Contacts always end up out of date on your phone
You get a contact, it lives there for years but they are probably out of date in no time at all and how do you know? When you try and contact that person and can't find anything that works? Why don't we have a service that you can opt in to that allows the update on contacts to be pushed to contacts? Linkedin asks when you change your title, "do you want to share this with your network?" Why can't we do this with your contacts too?
WhatsApp currently does that i.e. 'Notify contacts' after changing the phone number - https://faq.whatsapp.com/android/account-and-profile/how-to-change-your-phone-number/?lang=en , perhaps other chat apps does that as well because they are the once having the ability to sync and message contacts.
But I don't use WhatsApp or most other real-time communication apps, So this does that solution doesn't work for me and but it should for many.