&gt;1. Why is facebook required?<p>Because Facebook has a searchable, discoverable database of real names. Many people skip or haven&#x27;t gotten to the &quot;write down each others&#x27; contact information&quot; step but still want to talk to each other. Actually there is a deliberate, important progression in a relationship from using Facebook Messenger to exchanging cell phone numbers.<p>&gt;2. Are many people you know actually going exclusively to facebook as their sole communication method?<p>Yes. Some people have international friends or care about proper handling of long messages, delivery confirmation, read receipts, etc. excluding SMS. Some people have friends with Androids, excluding iMessage. Some people have friends with Outlook.com or Yahoo email addresses, which excludes GChat&#x2F;Hangouts. People are too scattered around Whatsapp&#x2F;Telegram&#x2F;WeChat for any of them to be worth anything. Everyone has Facebook. The cognitive overhead of &quot;Which of 8 different services do I use to talk to this particular friend?&quot; is fucking annoying and people avoid it by just using Facebook.<p>Many people in my (millennial) generation touch their emails as little as possible. Email is for bosses, professors, receipts, and annoying mailing lists. People I know are as likely to write a social email as they are to walk to their local Western Union office and ask to send a telegram.<p>&gt;3. Is it a conscious calculation for you&#x2F;most people you know?<p>Yes. Facebook is the only option inclusive of everyone, even those with the cheapest, broken phones that are out of free space.