Chromium being open source is not a mistake. Letting google be the sole driver and not forking it has been. People who want control over their browsers have options. It's a fight because most people don't care about these things.

There is no “browser business,” because people are - with rare exceptions - unwilling to pay for a web browser. Even Firefox is ad-supported indirectly via its default search contract with google.

Right. For example, Firefox Mobile doesn't support hitting ctrl+T to open a new tab, completely breaking flow for anyone on a tablet with a keyboard or their phone docked to a monitor.