I want to say that while it's a compelling argument you're talking about a hypothetical grow that really has as of yet to happen outside of the government. With that in mind we can assume that it would most likely be extremely cost prohibitive.
You are wrong about it being a hypothetical grow. Just because you have never seen one that was highly successful does not mean it has never happened.
Two boards ago, one that is now defunct, a member came into a large sum of money and decided to scrap his 1000-watt setup and go all LED. It did cost him a TON but then he had a TON to spend and money left over.
He researched and found the highest grade LEDs sold at the time. He had two large panels above his grow and he took bars of LEDs and attached them to what I call portable posts. He used 4x4's with a flat plywood bottom for balance and made some so they could be stacked on top of others making each one taller as needed. (If I were making the same thing I would use PVC tubing myself.)
He ringed his plants with portable posts with LED light bars on them. Between his plants he placed more portable posts with LED light bars on them, but on all four sides so they would direct light in all four directions.
He started out with his top panels low and his portable posts the shortest they could be. As the plants grew he raised his top panels and when there was enough height he would then add another section to his portable posts with another LED light bar, or bars in the case of the ones with four on each, and continued that until his plants grew to full size and it was time to harvest
He grow thread started with the construction of his new grow setup and ended with his dried and cured harvest, and it documented everything every step of the way.
His plants were the most impressive looking plants I have ever seen grown indoors. They were thick and lush and covered with buds. The colas were massive and even his lowest buds were about the size of buds I see most people get from just below their colas using a 1000-watt light.
It is the only grow like it I have ever seen but it was also the most impressive indoor grow I have ever seen.
That is when I came to understand that what I had believed, and what people like you say, that LEDs aren't all that useful, was totally wrong and that IF someone purchases the very best LEDs made and IF they purchase them in adequate numbers and IF they know how to use them in a way to get the most out of them they will easily out perform any other form of grow lighting.
But most people purchase inexpensive low grade LEDs and even if they purchase quality ones they expect far to much from them and they purchase to few and since so few people have any actual experience with them, especially in a properly designed and built setup, almost no one knows how to use them to their full potential.
IF someone can afford the very best and afford enough of them to be able to grow tall plants and IF they know how to use them to get the most out of them they would throw rocks at every other form of grow lighting and never consider going back to HID lighting, let alone crummy CFLs.
So no, what I said is not hypothetical. I have seen it and I have seen it work and I have seen it outperform any and every other source of grow lighting, so don't fool yourself into believing that just because you have never seen it that it has never happened, that it is hypothetical, or that it cannot and would not work absolutely fantastic ... because they will IF someone does precisely what I said is needed to be done to grow with LEDs.
If they don't then they should never have wasted their money on LEDs unless they just want them for mothers or clones or vegging to a short height. But if they can afford it and if they do it right they can end up with results that would make not only your jaw drop but the jaws of about 99% of growers who do not have a clue what LEDs can actually do.