i agree that stalls are neither good or bad, as it depends on how they are used.
If you were to ask if stalling horses , with little turnout, was bad, I would give you a definate 'yes!
We know so much more about horses, and what is best for their health now, that the fact full time turn out is better for horses, for their mental health, for digestion and hoof health, can't be disputed.
Horses are designed to being able to move almost constantly.
Horses also have great ability to adapt, thus can accept being stalled short term, and in fact, can even be made to 'love their stalls', as horses are creatures of habit. Does not change the fact that movement id vital for their mental health, for hoof health and for digestion
Thus, we often stall horses for our convenience. A show horse, a horse in full time training, ect.
When it becomes 'bad' is when the idea is used that some horses are too valuable to turn out, thus those horses, even young growing ones, are kept from having the movement that will ensure their future soundness, building strong bone, well developed back of the foot, ect
Horses that become stressed from confinement, are given medication, to help them deal with ulcers that result, become cribbers and stall weavers at times.
We get temps that drop to MINUS 25 F and beyond, yet all my horses are out full time in the winter.
Horses are much healthier with full time turn out, a wind shelter, aaaand lots of room to move, allowed to be a horse.
Thus, if you stall, ask why, and make sure your horse gets regular exercise
I don't ride regularly in winter, and if my horses spent a lot of time stalled, I would be forced to exercise them, for the sake of their health
I do have a barn, with four big stalls that have rubber matts and commercial stall fronts. My horses are not out almost full time, year round, except before a show, not because i have no stalls, but because I relaize what is best for them.
They are great when I need them, for a horse that needs stall rest, when I had new foals in early spring, and weather was bad, ect, but I no longer consider regular stall time the best horse keeping. I did , in the past, esp for any show horses. But then, I also thought in those days, that any horse you showed, had to be shod!