Sometimes they do both (help and hinder) Guess you don't want to add a third option to your poll do you?
When you think of 'breed standards' they cover many different aspects of an animal depending on the species,
such as weight and height, legs, head, the list goes on and on.
And depending on the species, a breed standard for say, height or weight may be one thing that hinders and the breed standard on say their top line or shoulders might help. In some species breed standards change over time sometimes to a point that the animal no longer looks nor can be used for it's original purpose and some call that 'improving' the breed.
And I'm not talking Mini's as I'm new to that world, I'm talking about many species in general (rabbits, dogs, goats, horses, etc)
Sometimes what one calls 'bettering the breed' actually ruins it's original design for it's intended purpose.
Added later, in dogs many breeds have color requirements in their breed standard and off colors are not allowed
and may times culled at birth. If an animal is 'quality' in every other aspect and we're not talking blindness nor deafness who cares what color the darn thing is. And dogs who use to be low to the ground are now bred to be taller than they were 20 or 30 yrs ago and
at times due to the additional height and lack of bone can't function for their intended original purpose.
This is a lay persons opinion as I am not a vet, nor trainer, nor handler.
And I find in todays society people want teeny tiny or HUGE disregarding the 'average'
And I am talking in general terms, not with Mini's.