Murphy's Law. If It can go wrong It will.

True that, just trying figure out that mick's dirty tricks so I don't get pinched by his traps again. LOL

You are using locks of poor design if you get waterhead with an oversized lock. Not all locks are created equal.

No I dont use oversized locks.
I have snared thousands of animals.

I have snared thousands of animals as well...with oversized locks. Including leg snaring. How many locks did you try on smaller cable to reach the opinion you have?

What is the reason one would prefer to use an oversized lock?

I use different locks for different animals,have used them all,discarded many.
Like all things trapping related simplest is best,for cats and fox I have settled on two locks the dmd adams and the cam.
For wolves I use a wedge cam with a kill spring.Occasionally I use a thompson type(hole lock) with a kill spring.
For beaver under ice you dont need a lock of any kind if you use beaver wire,for cable the dmd adams is it.With the correct size lock for the cable you will catch beaver by all extremities which is not uncommon using under ice baitpole.It is imperative that the lock up is solid when you catch by foot,tail, nose,or toe tooth etc.
Rabbits and squirrels i use wire so no lock necessary.

The reason some trappers I believe go to an oversized lock is because they dont know how to correctly construct an efficient closing snare,and have problems with a closely fitted hole lock binding which will not happen on a properly constructed snare.

Like a lot of fur handlers they try to make up for deficiencies by taking shortcuts which create a lot of problems they dont even realize.

Speed and strength. Especially when you deal with things like hogs.

Boco, again, a good lock design even used oversized will lock exactly the same on smaller cable. I have even caught nutria and armadillos by the tail.