When I started riding they were very clear with their weight limits. We had one girl that we considered "really fat" (176lbs) and I remember that she was probably allowed to ride 4-5 horses out of 20. I still know quite many ranches who have a 187lbs limit for any rider and you'll hardly find one here that allows people over 200lbs on their school horses. But the thing is - the fats just buy there own horses and no one can stop them. And in online communities they pamper each other like they always do, telling +280lbs obeasts that it is perfectly fine to ride a larger pony. And I'm sadly not joking, the internet is full of them. And I see way to many chubby girls on rather tall but fragile ponys...