Our society encourages most people to be lazy & unimaginative, who then would rather pay a bit more money to get something readymade than go through all the steps you outlined. Same reason why all those recurring subscription cooking ingredient boxes are so popular.

This is wonderful, because if it weren't the case it'd be much harder to start a business. So congrats to the founders of that website on capturing money by firing up Photoshop and copy pasting some patent diagrams.