Why? Because I can and it is the most efficient way to do it in the current snake room.
During the winter I maintain an ambient temps of 76/78 in the room with a oil filled heater and provide a hot spot, when temps start warming up the snake room naturally gets to 84/86 degrees (the room is located right under the roof), I could use the AC get the ambient temps to 76/78 and provide a hot spot but I found it counter productive and energy inefficient when all I have to do is simply take advantage of the room temp as it is. The care is the same their core temps is about 85 which is warm enough to facilitate digestion.
Now for someone who gets started I highly recommend to start of with optimal temps and gradient of 78/80 and 88/90, once they become experienced, feel comfortable enough and know their animals I would encourage them to find what works for them and their animals. (There are many successful way to keep those animals)