I'm not sure if this is fact, but it's what I was told years ago by various distributors and one manufacturer.
They all stand firm on no wet method applications because of some of the ingredients of the media itself. Years ago, most, if not all reflective vinyls had metal in them and the water helped to make this stuff mildew, lift, peel, turn colors or just not perform the same as other vinyls. Therefore across the board.... no wet methods allowed for reflectives.
Today, I don't know if it's made the same way and there are many more companies producing this stuff, so I would venture to say you can get away with the wet method based on what brand you're using.
I don't think making a broad statement about wet on reflective that it makes it Okay. I would think discussing what brand, color and surface you're applying it to has more to do with it than the method of application. You're kinda asking the question backwards.