Uh, as a frontend developer, I am kind of _shocked_ I've never read this before. There's a lot of fascinating parallels to modern web development. zitterbewegung noted the similarity to complaints about Electron apps' memory consumption, for example, but:

> The right graphical client/server model is to have an extensible server. Application programs on remote machines can download their own special extension on demand and share libraries in the server. Downloaded code can draw windows, track input eents, provide fast interactive feedback, and minimize network traffic by communicating with the application using a dynamic, high-level protocol.

Certainly sounds a heck of a lot like how web applications work (even though we're currently terrible at sharing libraries, heh).

> X gave programmers a way to display windows and pixels, but it didn't speak to buttons, menus, scroll bars, or any of the other necessary elements of a graphical user interface. Programmers invented their own. Soon the Unix community had six or so different interface standards.

Now _that's_ certainly familiar. Sure, the DOM is a heck of a lot closer to a platform for displaying complex UIs than X was, but it still falls so far short of what developers need that a plethora of frameworks, UI libraries, etc. have appeared and fragmented the community. You could also stretch a bit and say things like Google's work on web components are an attempt at a Motif-like standardization around one questionable standard, but I don't know if I'm quite cynical enough to make that jump.

> Even if you can get an X program to compile, there's no guarantee it'll work with your server. If an application requires an X extension that your server doesn't provide, then it fails. X applications can't extend the server themselves -- the extension has to be compiled and linked into the server.

While a lot of new browser features are polyfillable, a lot of the more advanced ones (e.g. service workers) are not, and users and developers are at the mercy of their browsers, much users would be with their X servers.

> Myth: X is "Device Independent"

The quirks discussed in this section apply to responsive web apps too. There's actually quite a bit of nuance in making fancy canvas, WebGL, or CSS transforms that look good on retina screens, etc.

I'm sure none of these comparisons truly map 1:1 to X development (having never done it myself), but damn if it doesn't remind me how cyclical software development has been over the past few decades. Not that that's a bad thing, just that some things are very, very hard :)