As an individual having focus on one thing is great but having everyone in a group focused on the same thing can be detrimental. Too many cooks in the kitchen.
Besides, even if we wanted to get everyone focused on the same thing it's almost impossible to do practically. Ironically, this desire would lead to centralization, the very thing we set out to avoid.
People's desire to build comes from their different views and beliefs about the best way forward. Like it or not it's going to happen that way regardless. That's healthy in a free market of ideas.