There are a lot of old folks who have always done it that way, and will continue to until they can’t. I have seen Class A’s do it as well that some pickup’s. These same people believe they need to idle it for a long time before turning it off too. By the time you get to a hiway or from one to a campground, the engine, tranny, turbo, oil will all be at a go/stop status. This is of course unless you camp/park by the side of the road...
On my gasser which too needs to warm a bit, by the time I crank it, let the levelers come up, slowly roll to the camp entrance all is good. I will let my toad idle for 5 minutes of so before starting the MH cause GM says to. But never at 6.
And although you inserted the disclaimer you know that’s exactly your intent... :B