Every text you've ever gotten from a business came from a five-digit number that couldn't answer a question. Reply with anything other than STOP and nothing happens. That's a 1985 design decision still running your dentist's appointment reminders. SMS got 160 characters, no sender identity, no memory, and no way to take money. So businesses gave up on it as a conversation and used it as a megaphone, then pushed the real conversation into an app you had to install or a phone tree you had to…