Maybe they could compete on having a better extension system. Chrome extensions are absolutely awful. Every single one I've ever used has had some kind of serious bug, often deal breaking. I could easily fix many of them, but there is no method to do so. Let alone fork it or submit a pull request. You can't even load your own extensions, and you have to pay money to submit them to the web store. A scary percentage of…
If anything, I'd say my experience between the Chrome and Firefox extensions are completely opposite to yours. For one, Firefox has some 1-3 different extension types/apis, so you have first understand which one to use from their convoluted developer docs. Secondly, when you submit the extension, some volunteer "reviews" it whenever they have the time, which can take days to weeks. Once I got feedback and got rejected because there was a typo in the extension.
With Chrome it's very easy to create an extension, you basically only need that manifest.json file and then you can submit it to the store and it's online less than an hour.