Don't forget battery life, roaming, discoverability etc.
The days of everybody having exactly one computer with a rarely-changing IP address are over. These days, most people have a phone which changes its IP address a few times a day (when you leave your house and switch from WiFi to cellular and then go back.) If you wanted to be directly reachable, you'd need to share these changes publicly, which would make it pretty trivial to figure out when you leave home, who you visit, which cafes with free WiFi you frequent and which countries you go to for your business trips. The stalking potential here is enormous.
The days of everybody having exactly one computer with a rarely-changing IP address are over. These days, most people have a phone which changes its IP address a few times a day (when you leave your house and switch from WiFi to cellular and then go back.) If you wanted to be directly reachable, you'd need to share these changes publicly, which would make it pretty trivial to figure out when you leave home, who you visit, which cafes with free WiFi you frequent and which countries you go to for your business trips. The stalking potential here is enormous.