TL;DR: to allow users to make contacts without revealing their phone numbers, but avoiding creating new surfaces for harm (spam, abusive usernames) in the process (which also eliminates all the issues that username moderation would bring).
TL;DR: to allow users to make contacts without revealing their phone numbers, but avoiding creating new surfaces for harm (spam, abusive usernames) in the process (which also eliminates all the issues that username moderation would bring).