Yeah, well, as I said, there have been all kinds of approaches to tailplanes and trim.
In most (if not all) Mooneys, the
entire tailcone (roughly the back 20% of the fuselage, including all the fins) is tilted for pitch trim. With a
horizontal jackscrew pushing and pulling the hinged tail rather than raising and lowering.
I guess one would have to get hold of internal Boeing memos 1964-67 to really know what their reasoning was for the basic geometry of the 737 THS. Or maybe even those from the 707, which had a similar general arrangement - "if something works, let's keep using it."
Not that it necessarily worked perfectly even then - note this 707/720 crash in which aerodynamic forces from
manually-set nose-down trim in a storm updraft resulted in a steep descent and high speeds that also apparently made retrimming physically impossible (possibly complicated by a slip-clutch to prevent breaking the system with
too much applied retrimming force):
https://lessonslearned.faa.gov/ll_main.cfm?TabID=3&LLID=66&LLTypeID=2