Why does the F-16 have a fixed stabilizer section inboard of the stabilators? So, we have a F-16 chilling on the ramp, showing us its tailfeathers:



Interestingly enough though, inboard of the all-flying stabilator sections, there is a fixed stabilizer section (this is quite clearly visible on the right due to what the stab is doing on that side).  This isn't universal on stabilator-equipped aircraft though, or even fighters, as the F-22 appears to have its all-flying horizontal tail hinged at the fuselage joints:



and the trimmable stabilizers on airliners are hinged at the fuselage-stabilizer joint as well:



So, why is it that the F-16 doesn't follow this pattern? Is there some aerodynamic design reason for that?
The F-16 has an all moving tail plane all right. What you are referring to as the 'fixed part' is actually the fuselage portion which houses the air brakes. It can be seen clearly in the following photograph.



Belgian AF stabilizer; image from designer.home.xs4all.nl