Idk about that garden, so I can't comment. I ignored that user several months ago. His panels were designed by the main contributors of the LED thread and he simply copies and repeats. No real information or usefulness to be found in his posts.
I mean yeah, you're right, if you just want to slam out a garden with as little effort as possible, then HPS is simple and cheap. It's not the best, but it works. People have been growing weed with HPS for a long time, so we know it can be done.
COBs can compete with HPS, it's that simple, and that's pretty much the end of it. You can ignore data if you want, but that's all you and not the LEDs. Are there LEDs that grow shitty weed? Yep, but I don't use those. I have used them before, so I know they suck. But the high density LED arrays are a completely new ball game.