There was a time when Gecko wasn't a very good rendering engine. And that was a time when practically nobody used Gecko-based browsers; it didn't really take of

There was a time when Gecko wasn't a very good rendering engine. And that was a time when practically nobody used Gecko-based browsers; it didn't really take off until it started to surpass IE. The useful analogy here is that Gecko had all sorts of room to improve and ultimately beat IE, but Theora seems to have little or no room to improve to the point where it'd match or beat H.264. Which means Theora will likely always be a fringe codec, just as Gecko used to be a fringe browser engine.