That might be, but continuous personnel replacement would be hard for both the abusing company and its customers. Disney wouldn't be so keen to outsource if they knew all the people they train now will be gone in a few months. It would also dry up the pool of applicants faster at the other end, especially if linked with provisions forbidding reapplying for X years.
Sure, but those companies will get spotted and the H1-B applicants won't work for them. It's easy to hide that you're an H1-B sweatshop and blame the government when you don't have to answer anything for 5+ years. It's not so easy to hide when 12 months is your limit.
People want to be part of the H1-B program so that they can get out of it--either by green card or by going back to their native country with training that makes them more profitable back there.