I am not saying that is always indicative of execution but I don't think Mozilla has any indicative of good execution? Hey, they invented a new programming language to reengineer the browser. The programming language is very succesful and it is growing in market share but Firefox continues to be written in C++.

IMHO there is a room for innovation in this space, long term but you can see if this happenning observing the project. Currently browser engines are one of the most complex pieces of software. There are new ways to attack these mammoths.