1. With NAT and metropolitan area networks, hundreds of thousands of devices could share the same public IP.
2. Large networks with many devices often connect to the public network through trunking (load balance the connections through multiple routers), so the HTTP connection between OKTA and my browser can VERY well originate from a different IP address than my SSH session, and I would never be able to connect.
3. Many devices are mobile, and they can change their IP address when they pass from WiFi to LTE for example. This would force an unnecessary re-auth.