So distance hiking trails take place on what some hikers call bicycle trails. They're usually gravel and asphalt. And some developing distance trails call this off-road. I'm here to shed some light on the topic.
By government declaration, these are often categorized as "multi-purpose trails" as per the record. The North Country National Scenic Trail, which I'm more familiar with, certifies these segments. And even of they're not, there's still "political correctness" to consider. Hikers of an Appalachian Trail origin will state that these aren't off-road. But if the distance trail agency didn't classify these as off-road, then somebody will pop up and argue that it is. On the internal side, I can easily see a "damned if you do, damned if you don't" type of situation.
Mid-west distance trails sometimes take place in urban areas and surburban counties. Going off-road in those vicinities would be very costly because properties are smaller and cost more.
I know a lot of this is observation and opinion, but disrance trails go from Point A to Point B repeatedly for a reason. That much is certain. You could come out of college with $100,000 in student loan debts and be very book smart. But more often than not, that barely holds a candle to experience.
Its hard to name them all. There could be internal commitments involved? I have to admit that I know a lot and have done great things, but I'm not on top of everything simultaneously. Basically, I'm not always good at delivering "instant gratification."