It's very easy to dissapear up your own backside with "what if" testing conditions.
In this case, you'd have to have two separate failures, a flap linkage failure, and a jammed lever, to give you asymmetric flaps that you couldn't correct. Both are highly unlikely events (notwithstanding that you experienced one), multiply the two by each other and it becomes absolutely tiny.
There's also a general requirement to make all systems jam-resistant.
G