In MANY other situations, and for simplicity reason, a character is very often rigged using just a simple IK setup (for arm, leg, etc) without FK switcher.
This would work for most animations and "just IK controls" and also good in the sense that Gimbal Lock will never happen for animator. Although, really for natural motion of joints, animators always like to have FK control too at some points.
Thus, in situation where the character rig is already animated and the animator wanted to have FK control, what should we do? Use Maya's built-in IK FK switcher is the simplest.
The good thing about Maya's built-in IK FK switcher is that it is already come with "snapping" script (albeit a little hidden unless shown in the Menu).
The bad thing about Maya's built-in IK FK switch, is that it is NOT very intuitive, unless someone is showing you how in easy step-by-step.