Since he says it was made by his friend im guessing because he probably didnt have the equipment to roll the stainless steel into a tube or pot shape. It was probably easier for him to weld up several sheets of stainless.
What's scary is he will ship.."unassembled".....I dunno. I have a home made 15 gallon SS pot myself. But it's round and I love it...Square just doesn't seem right...Oh well to each his own and to each his means I guess.