I believe that it is foolish to totally reject the idea of a possibility of a tire going flat, putting undue pressure on a slide out supported with some device. It could happen, and one doesn't need to have experienced it, or for anybody to have experienced it to realize the possibility and to avoid it.
for the record, I have never seen it happen and yet I never supported my slides with external devices.
sort of like the folks who say that they have never used a surge guard and have never had an issue. I still use one.
bumpy