You might ruin your slide that way. Now not enough of the movement from the inside of the rest of the rig might knock the slide totally out of it's track. It's not made to be supported. They need to move with the rest of the movement from wind on the outside and foot traffic on the inside.
In this case, the slide was completely off the track. The wall/slide has seen water damage over the years, putting it back on the track wasn't something I felt would work. I would never recommend this in a newer trailer for the reasons you said, but for me this works and gets me back into the trailer.
