Why do they have to reinvent the wheel?

Yes, but 5/8 hex. Also a two piece design. The long snout, or barrel below the tapered seat tends to seize in place and break off when they're changed. There's been at least three TSBs on how to change the plugs without breaking them, and how to remove the broken pieces when they do. Lots of companies making money off of tools to remove broken plug pieces because Ford decided to re-invent the spark plug.