Google selling Android as both open source and open to running any software you like in order to quickly gain market share, only to break those promises after driving competing platforms out of the market is nothing more than fraud.
yeah "Google has pretty clearly done an extremely bad job" at making competitors obsolete. Intel, Samsung, Nokia, etc. are all tiny companies who had no chance anyway, especially at the time before Android was firmly established as one of two platforms mobile developers bother making software for
Imagine, if you will, an adblocker that could run across not just web pages but all apps, in a privacy-protecting and declarative way. Google has every incentive to simply slow-walk the OS-level support necessary for this kind of system, perhaps citing legitimate security concerns, but certainly not allocating resources towards solving the problem in earnest. And if you hard-fork Android to do this kind of deep work, rather than just maintaining packages or patchsets, you'll be forced to dedicate tremendous resources towards maintaining that fork to keep up with mainline fixes/APIs. (And that's just the tip of the iceberg.)
So it's an incredibly effective chilling effect in practice, quite intentionally so.