Microsoft can push Edge on Windows users that don't know any better. They also aren't concerned about the web, as long as Edge is a vehicle for Bing and their ads. In that sense, Microsoft's interests align very well with those of Google's.

Chromium is controlled by Google and their interests. It is Open Source; however, Google has complete control over it, even though it has other contributors as well. Yes, it can be forked, should Google's stewardship go entirely wrong, but doing so would mean spending many resources that most companies can't afford.

To give an ancient example: ActiveX. Which Google almost copied in Chrome via NaCL / PNaCL. Mozilla with Firefox stood their ground and proposed Asm.js: https://en.wikipedia.org/wiki/Asm.js — out of all this effort came WebAssembly, which is more well-defined and at least smells like a good standard.

Other examples that Google would've wanted to push as de facto standards — Dart, and AMP: https://en.wikipedia.org/wiki/Accelerated_Mobile_Pages

Now, of course, depending on where you're coming from, you might view these efforts as being good. ActiveX was good as well, many apps were built with it, it's where XmlHttpRequest (AJAX!) comes from. It also locked people into IExplorer and Windows.

Yet another example that should speak for itself — the deprecation of the Manifest v2 APIs that make good ad-blockers work: https://ublockorigin.com/

And yet another example: Firefox for Android supports extensions, whereas no Chromium fork does. There was a Chromium fork that tried doing it (Kiwi?) but at this point it's discountinued, as the burden was insurmountable.