>Google makes some of their most valuable IP - Android and Chrome - (mostly) opensource and open platforms.
This was out of market necessity. They likely wouldn't have open sourced either if they thought they could have dominated the market without it.
Moreover, with both of these products they're drip feeding more and more functionality into closed source appendages (e.g. google play services). Their end goal is likely to ensure that if they did de-open source the whole lot, it wouldn't be possible to just fork it.
What most people consider “Android” - open source + all of Google’s proprietary add ons is not open source. A true AOSP only phone would not sell in any kind of volume in the US. Google yields a lot of power over Android based on its add ons.
Every major tech company open sources software that doesn’t impact its compatibility and encourages adoption of its platform.
This was out of market necessity. They likely wouldn't have open sourced either if they thought they could have dominated the market without it.
Moreover, with both of these products they're drip feeding more and more functionality into closed source appendages (e.g. google play services). Their end goal is likely to ensure that if they did de-open source the whole lot, it wouldn't be possible to just fork it.