When a user turns off the highway notation in their app, remember, it will STOP routing on "Minor Highways." So if you label a "Major Road" a "Minor Highway," it will be INCREDIBLY detrimental to the users directions.
I'm not sure what "turns off the highway notation in their app" means. This entry used to say that if a user selected avoid highways, that would include minor highways, and would cause routing issues if minor highway was used on a major road. It looks like that one line was removed, but this part was left in.
Or am I misunderstanding what the Wiki is trying to say?