I'd say there is a huge difference in the numbers of each that have had this particler thing happen. First, when my bikes ever blew up, it had full power, until I let off, and then, it went, wa wa waaaa. But even at that, I'm hearing much more percentage of riders experiencing motors locking up at bad times on 4 strokes. So yes, I agree, it probably does happen here or there on 2 strokes. But I'd bet my dollar that it is like 1:99 ratio. Most 2 strokes blew up, because wrong jetting, or didn't let their bike warm up enough. Mine blew up from the crank going, but, after my first and only, I always would take the cover off every season and feel the movement. If there was any at all, it was crank time. I can guarantee that my hours on a crank are atleast twice as much as on a same cc 4 stroke before they let go. We can pretty much protect ourselves from any problems on a 2 stroke. If you build it right, jet it right and keep maintence, not too many issues. On a 4 stroke, you have a good chance even if you do things right. It's called much more moving parts. If a 4 stroke had equal parts, let's say, I'd say they would have equal chance. But given the have so many more, it increases that many areas they can fail. JMHO
And let's not forget the higher RPMs they are running on a 4 stroke.