Be careful inferring that. The poll says "Not often connected," not never connected.
We know firmware updates proceed in pieces over time, and you get a upgrade notification once all the pieces are complete. There may be a similar mechanism for maps.
Some have said they got the map update notification when they were on cellular, but we don't really know if that means they received the last bit of data over cellular or if the data had finished updating over WiFi and there's some delay before the notification (background checksum verification and unpacking?).
I thought mine would be a good test since the only time it's ever been on WiFi is when it auto-connects at the Service Center, but there are so many people without map updates it's impossible to tell.