There’s a lot of fuckery there, and those of us that tried to build open source chromecast clones got fucked by Google as well.
If you wish to argue against this, please offer me a way to implement the Chromecast protocol on a raspberry pi, reliably, without it constantly being broken by Google’s updates.
Your argument that Cast is hard on unsupported platforms is irrelevant. They are, by definition, unsupported, and Google is under no obligation to support them.
Google provides an SDK that people are free to use on the platforms Google chooses to support.
The point is not about sending, but about receiving, as was possible with miracast, and which would have made the fire stick a killer product (by having immediate compatibility with all Google apps' casting feature)
How can they do that without also kicking out Netflix, Twitch, Hulu, etc.?
There were three groups working on such a receiver, Google with their Chromecast, Amazon wanted to support receiving chromecasts with the fire TV, and open source projects trying to receive chromecasts on the raspberry pi.
Google changed that protocol a few times, only Google's products can receive chromecast streams today.
And that was already after Google's anticompetitive actions against the Kindle Fire devices.
There's a separate protocol app → Google and Google → Chromecast. Or at least, there was, after countless changes, I gave up attempting to build a raspberry pi with chromecast support.
And of course, Chromecast replaced the dlna protocols and Miracast support in Android. I lost the ability to stream the screen on my nexus devices to open source receivers back then, because Google had to go proprietary.