It might work for you but there are a huge range of UTH heaters on the market producing various temps. I have a sample of industreal flexwatt (Holroyd rubber mat) that produces over 230ºC un regulated. Gap or no gap it would need a T-stat. You are making a blanket statement that simply is not always the case. If someone listens to your advice and their snake is badly burned how will you feel?

UTH comes in a wide variety of wattages and heat out put I have from 4w to 1200w units, the low wattage ones maybe you could the high wattage you would be lucky if it didn't cause a fire and shatter the glass.

UTHs need to be regulated!