[freediver]

There are two components of a modern browser: browser rendering engine and a browser framework (everything around the rendering engine that creates the browser itself).

There are three main browser rendering engines, all of which are open-source: Gecko, Blink and Webkit.

Problem of standards is mainly "offsourced" to these rendering engines and these open source communities have been doing their job more or less successfully.

Browser frameworks are built around these rendering engines. Two most popular open source ones are Firefox (built around Gecko) and Chromium (brother of closed-source Chrome, built around Blink).

I think the problem that you are articulating comes from the fact that 99% of browsers on the market use one of these two frameworks, in reality mostly Chromium. For example Edge and Brave are based on Chromium. This leads to inheriting most of the features but also most of the flaws of the browser framework.

Notably there are no major open source frameworks built around Webkit, which is a shame, considering that at least for macOS, Webkit is by far the most superior rendering engine (both in battery life and sheer performance).