While that sounds, on the surface, logical - I have a hard time believing that was the reason
Well...Since it doesn't really do anything other than the same thing that the standard guide rod does...that's the only logical conclusion I could come to.
And gunsmiths don't make the guide rods. They buy them from vendors who buy them from the manufacturers who make them to sell to people who want them...or who feel that they need them...for something. Standard or full-length...the cost is pretty close, and so is the profit margin unless the smith charges a premium for installing one...and that's a private matter between you and the smith.
I have, however, discovered a use for one. Firing a 1911 without a recoil spring in order to demonstrate that it can be done without ill effect and...aside from having to put the slide in battery manually...without changing the way the gun functions. The stub-type tends to get cattywampus and can do some serious damage without a spring to keep it straight.