Okay, but what does Firefox's ascendance have to do with a black market? It wasn't even breaking some hard to enforce Microsoft EULA provision. IE got lazy, and Firefox offered a dramatically better experience. Whenever a new product overtakes a more established competitor because it's better, is there a black market involved?

My purpose isn't (just) pedantic. You claimed "No, forcing everyone to use the same engine does not give the incentive to refactor it into something nice. It gives the incentive to create a black market.", but then your example shows an incentive to make a superior product. It starts making a lot less sense in Blink's case if you change it to the more accurate "No, forcing everyone to use the same engine does not give the incentive to refactor it into something nice. It gives the incentive to create a superior product." Why not a superior product that starts with a Blink fork?