A fixed-wing has many potential airframe failure-points,- certainly, there are plenty of youtube videos of badly damaged aircraft that keep flying against all the odds, but the average pilot would be somewhat challenged by 1/2 a missing wing or tailplane. A helicopterist ,by the nature of his craft constantly beating the air into submission, is, I suggest, more "keyed-up" (ok, as are crop-dusters, active -mission Military and display-pilots)
As MM pointed out, a great part of survival in an egg-whisk malfunction, is down to the continued integrity of the big fan on top. That, together with it's controls determines the chances of survival. Even a tail-rotor failure is not fatal, provided the pilot is on top of their game. "fly the disc" is the mantra, I believe.
Amateur builders know the risks of getting it wrong. The USA allows almost anything , AIUI in their experimental category and builders are treated as grown-up, allowed to make their own airworthiness decisions and Darwinian selection weeds out the thickos with more optimism than intelligence.
The development of the Rotorway Exec. is an interesting example of how amateur involvement works in the test-pilot and development scenario.
Perhaps it's time for an loosely or unregulated environment in more complex types,than SSDR. (the latter are not dropping out of the air like flies and the latest low-cost rash of newly developed ones is heartening to see,as it will ,hopefully slowly rejuvinate the currently shrinking and dying UK GA scene