Who uses XRender? If nobody is using XRender, is it because everyone is wrong or is it because XRender is not the best solution to the problem it's trying to so

Who uses XRender? If nobody is using XRender, is it because everyone is wrong or is it because XRender is not the best solution to the problem it's trying to solve today? And sure, X just transfers messages between clients, and the window manager is just a client, but it feels like X is redundant here - why not have a unified protocol so that the clients can talk to the window manager directly? That way, the window manager can actually delegate different functionality using some kind of an authentication mechanism. X was developed when the principle of least privilege wasn't as prevalent and it shows. I don't want all of my applications to be able to capture all of my screens at all times. Yet with X, there's no way to prevent this. And, may I ask,why are you so quick to dismiss the core developers of X?