From my POV, if it's required to use the product as advertised, it should be included. The manufacturer's recommendation that buyers find a way to fix their product so it's safe is absurd.
Mine are out in a coop with a run and a window so they get fair warning of dark approaching and will load their crops before tucking in for the night. Then they just sleep until the sun rises. No biggie. I'm not sure how it works if you put them in a place without those cues, though. Maybe leave...
It impedes the power so less gets to the heat plate. The linked ZooMed rheostat is often used to "dim" the ceramic heat emitters people sometimes use instead of bulbs. They'd probably work for the plate, too.
https://www.amazon.com/Zoo-Med-RT10-ReptiTemp-Rheostat/dp/B001OVD7Q8
Some of the plates get hot enough to cause burns?! That sounds like quality control issues, not an absent dimmer option. :(
I built one of the mama heating pad huts. $13 total cost because I used scrap materials with a purchased heating pad. I'd be furious if I'd shelled out the $ for a prefab...
Yep, I brood in a mini coop next to the big one and the youngsters eventually start entering the big chicken domain all on their own. It certainly makes the introductions less traumatic.
And I'm also switching over from heat lamps to MHP this time. I get a bit tired of constantly adjusting...