Some people have multiple addresses and it's hard to know which one they want me to use for sending personal messages. Plus their phone number! Plus their Discord, Whatsapp, Signal, Slack, Steam, Facebook, Twitter usernames.
What a mess! Which one should I use? Some people have been calling this the "App Fog" (https://element.io/blog/what-is-app-fog-how-do-i-solve-it/) for when you have so many apps and you need to remember which one to use for each friend.