You're confusing Chrome (the browser app) and Chromium (the engine that runs the browser). Different browser apps written around the same engine can have different features. Personally, I dislike having 4 different browsers on my system as "backup browsers" when Chrome doesn't work but Firefox does, for example. Having all websites tested under one engine sounds like a win-win for me.This "alternative" browser is pointless if the "alternatives" will all be just Chrome (and its variations). That will only put Chrome as literally the modern IE, and 99% of websites will only test compatibility with Chrome.
I hope the same "regulation" will also force Google to stop forcing OEMs to bundle Chrome on Android if they want their devices to be certified. I don't use Chrome on my Android, but it's there hanging around.