Open Source does that better than closed source, because it's impossible to get rid of the competition. Even if there's only one implementation, Open Source software inevitably competes with itself so even the author of that system can't close their own interfaces... if one really tried to force people to use a closed interface against their will, the community would just fork.

Open Source promotes Open Systems, which is why Open Source is important. Open Systems aren't a new paradigm, though, and the way Open Source keeps systems open... that's really a change in emphasis more than a paradigm shift.