Even if you go back to the carburetors with the "flood" button instead of a choke or primer, you always had fuel sloshing around on the base, and usually it had some dried grass to soak into, and on 4 strokes there was usually some oil as well. With the old British engines spitting through wire mesh air filters was also rather common. What was missing was an ignition source close to the base, where the flammable materials accumulated.
The bright idea of putting the ignition system under the crankcase, and simultaneously making the whole powerplant installation as low-profile as possible for appearance reasons, raised the stakes as far as fire risk is concerned: it brought the ignition source close to the flammable material. To operate those machines safely it seems to be essential to clear away the flammable materials frequently, and minimise leakage by replacing the plastic fuel taps as often as necessary. None of this was customary in the old days, so it is a bit surprising that there were not lots of fires as users retrained themselves. Fortunately I think the 2 stroke lawnmower is pretty much a thing of the past, and the risk does not exist with the types of 4 strokes that use suction fuel feed, magneto above the crankcase, and a decent air filter. That just leaves Hondas and other gravity-fuel-feed engines as having a slightly elevated fire risk, but not nearly as high as Powertorques because at least they have the magneto up on top.
