The issue with the OP software model is.... what happens when your phone goes into the lake like mine did this week? Not only do I lose contact with those people, I lose a record of the communications, groups, lists, etc. Everything is stored on the phone. Now it is lost. There is no central server that can restore any of it, including the accepted person to person connections. I need to use another tool to reach each of those people again and set the whole thing up again. And anything sent to me that doesn't make it through reliably is just gone forever.
I might hate text messaging but when I get a replacement phone my contacts will come back, people, people who could reach me before can reach me again and the messages that I missed are pushed back to me again.