Even in motorcycling circles, where engines are in a higher state of tune and tend to get used harder, crank failures are usually the result of a problem elsewhere (especially with 2-strokes ... oil pump failure, rings sticking & breaking, needle-roller small end bearings failing and dropping needles into the crankcase etc).

Many years back the crank on my 1950 MG broke, a diagonal fatigue fracture through the front main bearing - I was able to drive it five miles home as the only torque needed across the break was that to drive camchain and fanbelt

From my metallurgy studies (long ago) I think the usual material for steel crankshafts was some kind of 1% Cr/Mo alloy steel (known in those days as En19) or a Nickel alloy steel.

My MG crank fracture started at an oil drilling in the journal, had developed over many thousands of miles. In a fairly new car, either some material or manufacturing fault must have been present for a break to occur.

The question of DMF failure or a solid replacement is also relevant, without some damping effect torsional vibrations occur and may possibly lead to failure (though not commonly on short, stiff cranks, more severe on in-line sixes)