Yeah, over ten years and five laptops between myself and my partner, and maybe seven or eight power adapters (we've had spare adapters for some of our laptops), we haven't had any problems with fires, sparks, etc. As the parent said, though, "Not saying it doesn't happen"- just not to us, apparently.

I will say, however, that the MagSafe design, even lacking strain reducers as discussed by the OP, has proven its value on more than one occasion. Besides the obvious advantages (i.e., tripping over the cord no longer sends one's laptop flying, nor does it cause catastrophic damage to the power port), I'm personally fond of the fact that you can step on the adapter all day long without damaging it. We had to replace an adapter once back in the day after accidentally stepping on the little round connector part, and bending it irreparably out of shape.