Social dynamics are subtle. For example, group SMS doesn’t support contact names. If you add someone to a group SMS, the other people only see a phone number unless they go out of their way to add the new guy to their contact list. Likewise, the new person has to add everyone else to see names. Decades of research in behavioral economics show just how powerful defaults are, so most people probably won’t bother to add names. Without names, the new person will have a more difficult time connecting with the group.

This isn’t stupid. It’s the natural consequences of tech that doesn’t conform to real human behaviors and social norms.

Your argument fails when you consider Whatsapp - the biggest messaging platform, where you need to add people's number in your contact to be able to see their names.

I agree with power of defaults though. Only reason iMessage took off, and so did other Apple services.

You definitely don't... Unknown contacts show as e.g. "+1234567890 ~Bob" (their WhatsApp display name). When you save them to your contacts it switches to the name you added instead.

Exactly this about excluding names. I was sent a group message and didn’t reply because I didn’t recognize the number. I started another chat, deleted the number and then responded.