The fact that Vans guidance goes against conventional thinking, as you have pointed out, makes it hard to imagine that they put it in the FTS without some research and testing.
With a quick search, I found a 2016 Sling LSA safety advisory recommending the same - to turn on the lights to keep the B regulator from overheating.
Here is a note from that SA.
12iS SLSA #5
Salt Lake Int'l