There are different methods of framing a house and roof and builders do tend to specialize in just one. Balloon framing is different than platform framing which is different than mortise and tenon framing. To learn a new system, a carpenter would have to learn a whole new system of rules, measurements, suppliers, attachment methods, and seasonal tolerances. Here's an overview of some of these techniques: https://www.hometips.com/diy-how-to/house-framing.html

It's actually pretty analogous to programming methods.