Oh definitely don't do that if it's alone! But the whole point is that this animal should not be left alone to soak.
The point of the towel is to be a still moist landmass for it to feel comfortable on and reduce stress. Stressing an animal like this out in a soak can lead to it panicking and even at only 3/4 body depth, it can flip over or inhale fluid. It also gives them something to rest the front half of the body on.
I suppose you can put something flat and heavy they can't tip over in there, but they usually aren't able to get that permeability like a towel can. And that reduces how much hydration they can get through contact.
Part of the reason I started doing this for sickly reptile soaks is because of a coworker loosing one at 'proper depth' when it did alligator roll and inhaled too much fluid. =/