I suspect one part of the rationale behind this is that as Android has gained dominance Google has moved some core API functions out of the generic AOSP source-code (which everyone can use) and into the Google Play services which require the device manufacturer to sign a contract for, which apparently also includes terms that have - at least in the past as I understand it - required pre-installation (possibly in prominent positions) of Google applications.
On that basis there is a strong correlation with the anti-trust convictions of Microsoft over bundling Internet Explorer into the Windows OS which effectively destroyed the paid-application model for web browsers (Netscape - which had 90% market share - could no longer succeed whilst charging ~US$20 (UK£15) and (AOL/Netscape) transferred the code to the Mozilla Foundation).
apologies for glossing over fine-detail but I ran out of my daily parenthesis allowance.
I know that contractual conditions for Google Play aren't so easy on phone makers, but then again phone makers are free to build their own marketplace and ecosystem. I know at least Samsung tried it, their Galaxy phones shipping with a parallel marketplace, in addition with Google Play. Didn't work out.
I don't know specifics of things moved out of AOSP. If that's true, then there's some logic to it. But I did use CianogenMod without Google Play on it. It's still usable. Though certain things like Android's push notification system cannot happen without Google's infrastructure and that can't simply be free, even if the integration would be in AOSP. There might be truth to this, not saying otherwise.
On Microsoft, I blame them for many things, like for killing BeOS or for fueling SCO's lawsuit against Linux or now for racketeering in the mobile industry, but bringing anti-trust charges because of Internet Explorer and splitting them up (as was the plan) would have been a terrible and unjust ruling. Netscape killed themselves and sorry to say it, but Internet Explorer was not only free and bundled, but technically superior. And that was fine IMHO, because in its place Mozilla was born and the rest is history. Regardless, compare Microsoft of the nineties to what Apple is doing now with iOS. Makes Microsoft of the nineties look quite open by comparison, doesn't it? And can you imagine a phone or a computer not shipping with a browser included by default?
Speaking of browsers, Android is the only mainstream mobile OS that allows third-party browsers. Firefox is currently only possible for Android.
The U.S. remedy of splitting Microsoft up (which was over-turned on appeal) and led to the more limited U.S. Consent decree doesn't negate the findings of fact:
"Judge Thomas Penfield Jackson issued his findings of fact on November 5, 1999, which stated that Microsoft's dominance of the x86-based personal computer operating systems market constituted a monopoly, and that Microsoft had taken actions to crush threats to that monopoly, including Apple, Java, Netscape, Lotus Notes, RealNetworks, Linux, and others." [0]
In Europe the EU consistently found against Microsoft and fined them very large sums (> €1.5B) over the course of more than 10 years due to monopolistic practices and refusing to implement judgements around bundled media-player, web-browser and lack of interoperability for server (APIs). [1]
"Microsoft entered into a consent decree in 1994 that barred Microsoft from conditioning the availability of Windows licenses or varying their prices based on whether OEMs distributed other operating systems.[8] Microsoft General Counsel Brad Smith said that the decree was effective in allowing Dell and HP to offer Linux computers". [2]
This was later nick-named the Windows Tax, but at the time it prevented alternative OSs such as Digital Research DOS (DR-DOS) from gaining much traction as a pre-installed OS (I owned a company back then that did pre-install DR-DOS and it was much better than MS-DOS).
Regarding Google/Android:
"While it might not be an official requirement, being granted a Google apps license will go a whole lot easier if you join the Open Handset Alliance. The OHA is a group of companies committed to Android -- Google's Android -- and members are contractually prohibited from building non-Google approved devices. That's right, joining the OHA requires a company to sign its life away and promise to not build a device that runs a competing Android fork.
Acer was bit by this requirement when it tried to build devices that ran Alibaba's Aliyun OS in China. Aliyun is an Android fork, and when Google got wind of it, Acer was told to shut the project down or lose its access to Google apps. Google even made a public blog post about it:
"While Android remains free for anyone to use as they would like, only Android compatible devices benefit from the full Android ecosystem. By joining the Open Handset Alliance, each member contributes to and builds one Android platform -- not a bunch of incompatible versions." [3]
Also in that article is a good overview (albeit from 2013) of how Google has progressively moved open source functionality into the closed source Google applications.
And from a different source (lauding the move to Play services) there's:
"Google not only has pulled these services and their respective APIs out of the OS, it has made it easy for application developers to use them. The past few days here at Google I/O we've seen just how easy it can be to add these features to an app, because Google is doing all the heavy lifting. Developers only need to reference the particular thing they need from the Google Play Services application in their code, and the magic happens when you run it on your phone." [4]
On that basis there is a strong correlation with the anti-trust convictions of Microsoft over bundling Internet Explorer into the Windows OS which effectively destroyed the paid-application model for web browsers (Netscape - which had 90% market share - could no longer succeed whilst charging ~US$20 (UK£15) and (AOL/Netscape) transferred the code to the Mozilla Foundation).
apologies for glossing over fine-detail but I ran out of my daily parenthesis allowance.