For one, I can see someone blindly trusting it and avoiding roads listed as unpaved which are, in fact, paved. (As we know, not every paved road is available to check out on Street View, and satellite imagery can be inconclusive.)
Interestingly, this afternoon I looked at another route I mapped out maybe a month or so ago. It now shows a random 0.3 mile stretch somewhere in the middle of of an 8 mil road segment as unpaved when it's not. I am curious to know how something like that happens. It's not like it was paved any time recently. I think I first traversed that road by car 45 years ago on the way to a week down the Jersey shore.