Why Are Freehand Stems Partially Inserted?

[Chasing Embers]

I must be missing something. I thought that is the way a "military" bit was supposed to fit. Looks good to me.

Some do, but several in my collection, though sold like that, will actually go all the way to the base of the stem with no exposed tenon.

 

[Chasing Embers]

I thought the military bit was a metal to metal joint between shank and stem

In the case of a military fitment, you'd be right. Stems not made to fit the overall shape of the pipe, like freehand stems, are often called military stems just because they don't fit flush.