[Filligree]

And the reason they have this, is so that pilots can overcome a jam by breaking that linkage. Only half the plane will then be responding to the controls, but that's much better than none.

[WalterBright]

The rationale for this (I did some work on this system at Boeing) was that the pilots would not be fighting each other for control, they would be fighting a jam.

Flight controls at the time were not designed for dealing with a crazy or malicious pilot.

[p_l]

A stick to the head is the classic solution for a pilot going crazy on controls for whatever reasons. Sometimes the stick is not metaphorical.