This was certainly common enough knowledge that it was taught to me explicitly in Boy Scouts back in 1997. Preventing all forest fires builds up undergrowth so

This was certainly common enough knowledge that it was taught to me explicitly in Boy Scouts back in 1997. Preventing all forest fires builds up undergrowth so that the severity of eventual fires is much worse and they are less controllable. At the time, they were doing controlled burns of the Boy Scout camp (Philmont) in Nevada to try to make up for decades of undergrowth buildup before they knew better.