No. Done properly it's actually much harder than other techniques, as the ML needs to adjust the pressure by supporting part of her weight with her arms and the rails on the ceiling.
Also the sliding motions require a lot of whole body tension and control.
I know a ML who charges extra for backwalking - because it's more physically demanding.
If done well, back walking, knees, elbows and forearms can be much better than just hands. If done badly it can be painful and bruising, but it's worth it when good. A glute massage with the forearms can be amazing, especially when followed up with something a little more sensual.