The horse is advertised as 17HH, so yeah, you're right on that count.  It's a Canadian, definitely not a draft horse, but a medium-heavy breed.  The owner/obeast is looking for a leaser and promoting the horse as a (show and lesson) jumper: in all the pictures I can't see fences higher than 2.5 feet maybe, but she's definitely not "vaulting it" as you say or just picking it up over poles, the ham is at least trying to get it in the air.  And yes, horses are strong and athletic, but they're also delicate and prone to damage in their ligaments when they're used the wrong way for too long.    She's not being called on it because she owns the horse, the barn and promotes herself as a "coach"... so anyone who said anything would be quickly told to take their opinions elsewhere. And besides, in what fucking reality is this hambeast "only" 250lbs?  She's north of 300 by a safe margin.