I once had such a bike. It was too stiff, heavy, or what is the correct word -- but that was not the main problem.

Even though I put an extra cushion under my ass, the saddle still pressed some bone/nerve -- difficult to explain where, it is a inside the hipbone, very high there on the inner side of the thigh or actually the hipbone -- and I noticed that I could not continue.

So I probably could not bike any more even if I had a real bike, at least not a long time.