I guess they have been wrong all their lives cause it does work, i too was surprised when i removed power to the glow plug and the engine kept running, even a nice low idle, this was on a 21cc weedeater engine on 1 part glow fuel / 2 parts premium gasoline. As long as there's something to ignite the mixture, some compression and the mixture will burn, it will run, actually quite well on the glow/gas setup, i'm a believer.