Go figure. It's amazing the kind of nonsense people can be talked into believing against their own common sense.
Try telling these people (staunch heat lamp advocates) that they should keep a light shining on their baby at night and it won't affect them and their development at all. See what they say to that. I'm sure that something like, "well, chickens are different" will come forth. But that's a completely baseless point that is only meant to rationalize their position and clear the cognitive dissonance.
Whoa...down Trigger!

Heat lamps do have their place, even though that's NOT at my place. Very large batches of chicks would be almost impossible to raise under MHP unless they were split into groups and each group had their own brooder. You can make the setup bigger to accommodate like 30 or something, as @Fire Ant Farm
did, but those of us who believe so strongly in this system have to be careful that we don't become as militantly pushy about MHP as others are about lamps. We can show, explain, and use it exclusively ourselves, but after that we just have to let them do what they prefer without judgement.
Personally I'm on a crusade to get folks to look at alternatives....coop and house fires are so unnecessary and I think MHP is so much healthier for the chicks. But I try (not always successfully, I readily admit) to present what I have learned just to give another option. What they choose to do with the information after that is up to them, and arguing the point is counterproductive. (That's what my brain says...I wish someone would explain it to my fingers sometimes!) While I'm so happy that you are a MHP fan, remember that in the beginning you were a little uncertain too. Every one of us on this thread had little doubts when we started doing this. It's a huge leap of faith to expect folks to disregard years and generations of "care instructions for chicks" and let them self-regulate. We need to respect that, but oh, so often I find myself in a feed store watching people select their chicks and then putting the box of fluffs in the cart alongside the heat lamps and the worthless waterers, although not long ago that was me. I want to grab them and say, "DON'T do that".
Okay, off the soapbox.