They were originally developed for human males who had lost one or two to testicular cancer or accidents. It helped to maintain the self image of being "whole", of remaining "normal".
Somewhere along the line, someone anthropomorphasized a bit too much and figured that animals needed the same "self image". They don't. But some men (note: I said SOME
!!!) can be terribly insecure about such things, extending even to their pets. And for the show ring, I can entertain the idea that some (unscrupulous) owners would want to do such a thing to earn the awards, even if the stud part didn't exactly pan out.
My hubby balked at removing "the boys" from our boys. He physically winced at the idea. But he was able to read the literature and agreed, as long as I was happy to just have HIM "snipped"
.
Afterwards, the only thing I was concerned with was how long it would take for the "residual" (scrotum) to reabsorb (not long).