This is a great example of how intellectual property supports and hampers innovation. Board games can be protected by trademark, copyright and patents; patenting game used to be very common (I have a copy of Camelot from 1932 with the patent notice prominently displayed).

But these days board game publishers generally don't bother with patents. Dominion could certainly have patented its gameplay; but it wasn't, and so we have dozens and dozens of deckbuilding games pushing forward all kinds of innovations in game design.