None of that is chromium. Vivaldi could have built that on top of Firefox, but didn't. As to why Firefox is better, the very fact that it's an alternative that is keeping up technically is a benefit. It's less a 'V-shaped engine' monopoly and moreso a 'V8 engine made by a specific company' monopoly. They have far too much control over the direction of web standards. Much of what they are doing is actually good, but it should then be spread based on merit, rather than because they directly control almost the entire market.