Why not? I can load an IP database locally, so it's an option and a "competitor" to a 3rd party API. That's what I'm comparing it to, not against other APIs.
Maybe in this case. But historically, exactly this decision point has oscillated. It's caused reversals in distributed computer design for decades. First the networks were slow and disks were (relatively) fast - so each machine had one. Then networks went Ethernet, and disks started disappearing. Disks got down to a few ms access time and they came back. Then Gigabit came around. Then SSD.
Today I'd say it depends upon exactly what your network data source latency measures out to. The answer could go either way.