it just simply shouldnt be allowed or should we just keep dreaming of a crew like that

with crew like that I doubt I would be sailing

Although it's hard to concentrate on the rigging I was wondering what is the purpose of the device that's attached to the boom vang?

Answering this 8 yrs later, sorry.

That’s the boom vang. The boat has boom roller furling mainsail. That attachment allows the boom to roll.