I get the sense that Google cared about open protocols, and then Android changed that, to simply being another mechanism to lock users into their walled garden.
I don't think you can pin the change on Android. It's a slow progression at Google from the days of the unofficial "don't be evil." Even their official standards have been awful. IMAP was, and still is, hopelessly broken on gmail. Where GTalk once had XMPP with federation, they silently removed federation and XMPP entirely. I didn't realize how bad their Card/Caldav implementations where because I switched to Radicalie back in 2013.
There just isn't any money is letting users access and control their own data in a standard way.
