What good is iOS 17's offline maps when I can't get directions (navigate) when there is no cell service (internet access)?

While on a trip to Hocking Hills State Park in Ohio, I had the foresight to download offline maps for the area. However, when I found myself without cell services (it's very hilly there and cell service was spotty in places), and the Maps app showed me I was using offline maps, I could not navigate back to my rental. The app stated I needed internet service to route to my destination. This makes offline maps useless IMHO. My car has builtin Navigation system that works without internet connectivity. Truly offline availability. Perhaps it's an oversight on Apple's part. Even though Apple says you can navigate without internet services using offline maps. I would beg to differ.