Sure, and SMS is the protocol equivalent. A lot of email protocol communication has been replaced by private, non-open solutions such as Slack, forums, Whatsap

Sure, and SMS is the protocol equivalent. A lot of email protocol communication has been replaced by private, non-open solutions such as Slack, forums, Whatsapp, etc. There should be open and closed protocols. If you want to use an open one, then go ahead, If a closed one works better for you, then go ahead.