Well, Google has marketed Android as an open source operating system (AOSP) and openness about the system [1] and encouraged manufacturers and developers to build on it based on the premise of openness and of course being "free". People advocated for Android because it was open source compared to other alternatives. But with this change they are simply ending that openness. People that have developed F-Droid and other alternative stores have contributed to the platform value (such as not being able to de-google their phone), the same goes for many other developers who have spent countless of hours developing for Android.

To say they don't owe you nothing seems like a betrayal on the promise that Android was an open platform (and open source).

> You are free to not use their products or start a company to compete

That's not an option as you are making it out to be. For a user switching means buying a new phone, repurchasing apps (if you bought) and maybe apps won't be even available to the new system, for developers that means all their knowledge about the system gone. Building a mobile operating system requires millions if not billions of dollars, years of work and convincing developers and businesses (hardware makers) to use your operating system. The barrier to enter is so high that telling people to just compete with Google is not a realistic solution.

[1] https://blog.google/company-news/inside-google/around-the-gl...