Before 2008, smartphones OS market was fragmented.
There were a few big names like Palm and Symbian, but most phone manufacturers were doing their custom operating systems. For example, Motorola alone had five operating systems.
In 2008, Google came out with an open-source smartphone OS.
Mobile phone manufacturers like Samsung, Motorola, and HTC, embraced it and made short-term profits till they got commoditized by a standardized OS controlled by Google.
On the other hand, Nokia and Blackberry decided to ignore and badly lost market share.
Eventually, they embraced it as well, albeit, in different forms but it seems its a bit late.
The only winner (till now) is Apple, who was simultaneously working on iPhone and has held its ground well primarily, due to superior UI design and user experience on iOS.

Material Design

Till 2014, web design has been fragmented, flat design is popular, but no one controls it.
There are a few big names in web UI development like BootstrapFoundation but most companies are either using homegrown or open source jQuery libraries/CSS libraries for design.
In 2014, Google came out with Material Design, and just like Android, it’s being given out for free.
Even Android 5.0 is using the same material design.
While app developers are almost bound to replicate material design for Android apps, the choice of offering the design to web developers is an interesting one.
If a sizable chunk of web developers decide to embrace material design, Google will control look and feel of the web.
If the android apps and websites look similar, then it will only persuade more and more iOS developers to use material design in iOS apps.

The end game is to corner Apple in user experience by producing a design which Apple will be either forced to adopt or create something different and superior.
As far as others big players are concerned, both embracing and ignoring material design will be an equally lousy proposition.

Disclaimer: Thoughts are solely mine. 
Disclosure: I used to work at Google.