What's the point? To look pretty? It looks horrendous to me. Why would anyone want to make their horse do that? Adapt the structure of their neck and throat just for cosmetics? I've been doing more research on it, thanks everyone for your posts.
I've seen my pony naturally put himself in a proper frame while playing around in his field, my mare will work from her hind end like she should but not fix her head position (she's got a fat neck so I think it's tough for her to have her head down at all). But I've never seen a horse put his chin to his chest for longer than a second while moving. Honestly, you can put your chin down to your neck and walk around, but should you?
Think about the structure of their neck and throat, can this honestly be good for them? Seriously, try tucking your chin to your chest, you'll feel a strain down the back of your neck, do it long enough and you'll start feeling a little numb/tingly. You also can't see a darn thing, honestly what's the point of riding a horse so they can't see anything besides it's feet? I thought the point of dressage was to work in partnership with your horse, not to dominate over them and contort their body into horrifically unnatural positions.
When I say unnatural I'm referring to positions their body shouldn't naturally be in, clearly this isn't. Natural doesn't mean what a horse physically can do, with enough stretching and practice I could probably put my foot behind my head, doesn't mean I should
do it and it doesn't mean it's natural to put it there. Why should we distort our animals body's simply because it 'looks pretty' to some judges who clearly have no perception of beauty and are only looking for crazy extremes. I would rate this close to Big Licks, no matter how slow you train them to do it.