Once upon a time...you betcha. Most of those look very well built and I'd imagine there's some solid engineering done to make them very stable.
Nowadays...I don't do stairs too well, so I'd have to pass.
In the mid-90's I was working as a crane operator for a company that also had a tree service in the SF North Bay area.
I took a crane into Mill Valley where an engineer was expanding his hillside house. My company had gone in and topped a bunch of the large fir/pine trees downhill from his existing house, then, using the crane, we placed heavy beams that ran from the house to the tops of the trees. Those formed the frame for his new floor...about 50-75 feet in the air.
Once all the beams were in place and properly bolted together, and the joists in place, the new floor was as solid as if it were built on a concrete slab.
Everything was engineered and met the approval of the local building department.