The first time I saw this was right after the Texas ice storm and power grid failure a few years ago. A lot of people were suddenly stuck in their now unheated homes trying to get by with what they had on hand. Thay’s when people found out that making the most of the heat from a candle is better than nothing and word spread because most people had time to kill and the stuff to try it.

If you are careful about it you could warm cold hands or get a mild radiation effect if you’re close to it. But yeah it’s not going to heat a room to any comfortable level on it’s own.