It has always been my thought that the natural body and head position of a horse is what is best for him in terms of balance. We humans alter that by insisting on a low head, a tucked nose, and other changes different from the way a horse would carry himself if he could. Why do we think we know more than nature does about horse body positioning?
Some say the weight of the rider changes a horses balance. That may be but the horse is capable of altering his posture to deal with that without us telling him what he should do. He will naturally tuck his rear for certain manuvers and lower his head for others. Sometimes he wants that head high.
So is all this trained in collection really what is best for the horse? If we think so, how do we know that ? Is it a looks thing...that is... what we humans think looks good? We have taken natural horse gaits like the running walk and tried to turn it into some kind of strut with totally unnatural leg action...and doing all kind of barbarous things to get it. We work to get horses to nod thier heads, lift thier legs unnaturally high, carry thier tails in certain ways or drop thier nose so low they are practically stepping on thier curb strap. We crank their heads down with tiedowns, poke them with spurs and yank thier faces around with harsh bits. I'm not at all against training...but are we helping or hindering our kind friend the horse?
I completely agree with this. Imagine you are giving someone a piggy-back ride. You pick them up and carry them. Then someone watching says "no hold more with this part or that part" - don't you think you, the person carrying, would best know what's most comfortable for you?
At the same time if you want a horse to build up specific muscles they need to be ridden in a different way. I think the problem comes from people calling it"natural" or "correct" horses are natural without our interference. They carry us how they naturally feel comfortable, any interference is not natural. That being said that is what riding is, not natural. If you want a horse to have a strong topline and a nice neck then working in a collected way is ideal. But then you could also just get a horse who naturally carries himself that way so that you don't need to change a horse's natural way of carrying you.
As fun as it is to see horses doing different unique things I'm a strong believer in horses doing the job they were bred to do - as they do it best and they do it with less strain on themselves. Jumping horses are built and designed to take the pounding on their legs of jumping, as much as I like jumping my drafts I wouldn't ever expect them to carry themselves or ride like a hot-blooded jumper.
Where I'm going with this is, taking a horse who doesn't naturally collect and asking them to collect does cause strain on the horse, which eventually leads to muscle in specific attractive locations. But it isn't how the horse was designed to move and thus causes more stress on them than collecting a horse bred to move like that. Such as a lusitano or an Andalusian, it doesn't cause them much effort to move the way they naturally do. Collecting a QH into a 'frame' is going to put more strain than collecting an andalusian into a frame.
Each breed has been bred to have a specific silhoutte when moving naturally, changing that natural silhoutte causes strain.
ETA: I also do not compete. I also see no reason to need to control every inch of my horse for every second. I ride because I love it - my horse can move how she's comfortable, if she's not balanced in something I will work on it, trying to help her until she figures out how to balance herself - how she's
comfortable doing it.