> The security model of allowing apps access to your full filesystem (assuming your user has access) is flawed.

Your are neglecting the option of exposing a limited subview of the filesystem like containers do.

> But people are working on a solution.[1]

The big red box on top says it's not on standards-track.

> WebRTC while not the same and far more overhead (due to TCP sockets vs OS level sockets) can function very much like IPC.

Can I send open file descriptors like I can with unix domain sockets? Can I share memory for low-latency atomics? Futexes?

> So is X Window.

Maybe if you're remoting X, few people do that these days. In practice X applications have access to the same machine that they are drawing on.