We used to have one and it helped but it was a hassle for shorter stays as you would have to pull it out and then store it.
A bit more expensive but the JT strongarms (or clones) are more effective and less effort.
As to why:
- Wheels are on springs, so they will still allow bouncing.
- Simple vertical stablizers can only provide resistance to vertical motion. Side to side and front to back motion is unchecked. Adding a device that resists side to side and front to back will take a lot more of the motion out.
PS: As much as people like to claim rock solid, there will always be a little movement.