I'd also say an interesting thing here is that you (user) can instruct the client to assemble the furniture in a different way. Leave some shelves out or drill some new holes and move things around. Paint it a different color. Do some IKEA hacks to mix & match parts from different sets in ways not anticipated or condoned.
Sure, sometimes that means the end result doesn't perform as well or exactly as intended. But, I think these are key features of User Agents on the Web.