I mean, the people who maintain far and away the most used closed-source browser, IE[1], are deprecating it and have tried to distance themselves from IE as much as possible in Microsoft Edge. And this is entirely because IE lacks features that Chrome and Firefox have, largely but far from entirely related to standards support for HTML5. I have been using Microsoft Edge since it was available in the Technical Preview, and it is not on par with Chrome or Firefox yet as a daily driver. I hope it gets there someday, but it's not there now.
[1] Safari is kind of a border case -- all the chrome is closed source, but the rendering engine and I think the Javascript engine are open source. I am lumping it in as an open source project here, I can understand why someone might argue the point though.
Ok, I think it's reasonable to accept this. However one could equally well describe these open source browsers, as browsers funded by Google and Apple. Perhaps that's why they are outliers.
[1] Safari is kind of a border case -- all the chrome is closed source, but the rendering engine and I think the Javascript engine are open source. I am lumping it in as an open source project here, I can understand why someone might argue the point though.