Agreed about having it dialed in.
I get great results just with fresh air though. But I think your assessment applies as far as to why I do.
It's because these lights allow me to easily keep the plants in that perfect zone that they grow at very good rates. No overheated leaves, no tent poles and tent walls and buckets acting like the inside of an oven, no fans in hoods and ducting dripping condensation (I live way up north) etc.
No AC. About 1/3 the dehumidifier runtime I used to have.
Side by side, watt for watt, all conditions the same, there really is no comparison. I grew with HID for nearly two decades, and I would never go back. Not for anything.....except for the one advantage....if I am in a basement and I can't keep my room warm, it makes more sense to use a HPS to both light and heat it than to add a supplemental heater. But that's about the only advantage I see to HPS at this point.
My 600W replaces a 1000W SINGLE END (thought I'd better re-state that). So if I put a 1000W (actual draw) of QB lighting up against 1000W of HPS lighting in the same setup and kept all conditions the same, day in day out that 1000W LED is going to dust that HPS. Everytime.
Again, assuming all other conditions are the same.