Hmmm. I can't help but regard this technique as a 'domestic' cheat, less skill involved and it saves washing up the extra plate you need to turn it over in the pan. I think the 'tortilla al horno' is gaining in popularity now as a way to cut down on oil and make the tortillas less fattening (or more profitable, olive oil not being so cheap as it was)

As you said, more of a crustless quiche than a tortilla.