Microsoft could have written any browser engine it wanted and then placed iOS/Safari like rules on other browsers, such as... "if you want us to allow your app to run in Battery Friendly mode, you must ONLY use our OS provided web engine."
https://msrc-blog.microsoft.com/2019/07/22/why-rust-for-safe...
I guess Microsoft was tired of losing the browser game, so it decided to back the winning worse this time. But I still believe it will be a mistake long-term, as Google will start controlling Chromium's direction with more of an iron fist.
I believe someone else mentioned in a previous HN comment about the ad-blocking API that it doesn't matter if Edge, Brave, or other Chromium-based browsers can "continue to support a Chromium API if Google wants to kill it", because in the end if their combined market share is tiny, most developers will stop supporting that API anyways.
I imagine the Chromium browsers will be going in the direction of Android, where "anyone can fork Android" but in practice you're dead in the market if you don't back Google's Android.
Why am I bitter?
1. It hands a lot of power over to chromium, regardless of how much it gets forked by Microsoft.
2. It would have put some very talented engineers onto a Chrome competitor, which I always like to see
3. It would have been a huge boost to Rust, which if it ever will unseat c++/c as a systems language target, will need all the help it can get as a de facto standard (you can argue if this is worthwhile or just pie in the sky dreaming, I'll concede on that)
4. I just plain think we need a V8 alternative for a nodejs/electron like ecosystem, in my opinion servo could be that. I know they are doing node-chakra-core, but this could have taken it to a whole new level.
Competition is good, in another words. Even if all my assumptions are wrong, I'd love to see an alternative history where they were laid to bare.
Now, I will admit, I am actually happy to see that they are on Chromimum instead of yet another engine, and I see all the upsides of this move too, and will definitely take advantage of them (with Microsoft Edge being my favorite version of Chrome right now)