“but that shouldn’t be difficult.”
maybe, maybe not.
What IS difficult is making sure pilots know how to fly a plane with completely different flying qualities than the one they took off with.
Why go minimalist? why not have another fully-redundant flight control system?
triple, quad redundant how much more do you need?
Unless the two systems are designed independently, there's a risk that a systemic failure mode could hit both simultaneously. Even when using two independent designs, it's possible that some shared stimulus that wasn't anticipated by either design team could hit both systems and cause simultaneous failures.
I haven't flown any size of aircraft, but I would think that a pilot should, with a little practice, be able to fly and land an aircraft with a minimalist control system well enough to land the plane well enough for the passengers to survive even if the airframe may be damaged beyond repair. I would think the acceptable level of risk for trashing an airframe (bearing in mind that the pilot might land it undamaged even with the backup system) would be far above the acceptable level of risk for an all-hands crash.