[tremon]

https://en.wikipedia.org/wiki/Browser_wars#Second_browser_wa...

The growing number of device/browser combinations in use, legally-mandated web accessibility, as well as the expansion of expected web functionality to essentially require DOM and scripting abilities, including AJAX, made web standards of increasing importance during this era. Instead of advertising their proprietary extensions, browser developers began to market their software based on how closely it adhered to standards.

As soon as one browser dominates, one company gets to dominate how the web works. If you, as a user, want to be able to choose your own browser you should oppose one engine becoming dominant.