We stopped using these for a variety of reasons: they were difficult to make secure or cross-platform, GMail made building apps in JavaScript fashionable, and the iPhone (which explicitly would not support ActiveX/Java/Flash).
I think some things work better when they’ve evolved from simplicity to complexity, and application hosts seem to be one of them.
I don't think it's so much a question complexity than a question of using the "right tool for the job". Web technologies were never designed for that, never engineered to be extensible. Web apps is a hack, it's terrible, and that's all because of politics.
Like separating the text and widgets rendering engines, and placement engines with "stick" orientations.
If Tim Berners-Lee had made the web for apps and not documents, history would have been no different. Somebody besides Tim would have made a remote document system and we'd all be using that instead of something called the web.
The moment we do that; we can theoretically implement any GUI framework we like, rendering to a <canvas> tag, without the current (serious) downsides. I’m looking forward towards more exploration of that direction. Then, we can mostly be free of HTML, CSS, and JavaScript defining how apps can be built. Those three tools that have long outlived their original intentions and have gone into complete duct-tape territory.
AI however, might actually solve this sooner than we realize. Apple already uses AI to copy-paste text from images. I’m sure there’s plenty of R&D going on right now on using AI to describe what is on screen. In theory, maybe we can legitimately AI our way out of needing accessibility concessions, and off we go. Build your website in Flutter; or in MAUI; or in some DIY port of SwiftUI; whatever you want.
On the upside, most people don’t build their own frameworks. Implement it right in Flutter, MAUI, etc. in such a scenario, and almost nobody will be harmed.
Also, for anyone who just says this is Java and Flash all over again - we’ve had plenty of technologies come full circle. WASM might be the one that gets us to full “web as app engine.” It already basically is, just badly.
Silverlight, Applets, Flash, all have WebAssembly runtimes now.
This is somewhat like the leap Figma has made. They were able to build their own walled-garden, offer value in it, and not have to worry about SEO. Most of the web is not in that position.
I'd imagine we'd be better off with more such fragmentation, though?
The internet was built to allow fragmentation, of protocols, of tech, of connections. It is just that, of course, most sites must flow to where the easy $ are. Let's just hope that enough good sites can escape the pull of easy $.
We might reach the point of saying, screw it, it hardly matters anymore. The web has been conquered by LOB apps, Paywalls, and Walled Gardens; and there’s no real way to fix that, but there is a way to fix the tech we are using.
If anything, if we fully embrace “web as app engine,” we can fix some of these issues ahead of time. Maybe we have a standard entry point for crawlers (or users) requesting the raw text of a document. It’s better than being stuck in this awful in-between which we are right now.