| Because a modern browser is about as complex as an operating system, and moves even faster. Check out the complexity of ES6. You're gonna need an interpreter for that which performs acceptably well, plus a DOM interface to the rest of the browser. And check out how complex CSS is when it starts interacting with everything. Gotta handle all that too. Along with the basics of HTML structure, and how to interpret horribly broken HTML. And all of those pieces have to work together in realtime for dynamic animation, and do so fast enough for webapps to work and without eating too much of the host system's memory and CPU. And handle the constant addition of new JS APIs and how they have to interact with the host OS. Better be compatible and integrate well with Windows, OS X, and Linux too. Building a new one from scratch today is pretty comparable to building a new operating system. You'd probably need to coordinate thousands of people working fulltime to get it off the ground. And it's basically impossible to charge any money for it, since all of the tech majors give away fully supported mature browsers for free. In theory, you can fork an existing browser. But they all move so fast, keeping a fork with any useful changes up to date with the main browser is going to take a significant sized team too. Microsoft is a tech giant, and even they decided to dump their independent Internet Explorer codebase in favor of using a Chromium fork. Now the only other truly independent browser codebase is Firefox's, and they haven't been doing so great the last few years. It's probably practically impossible to build a browser that isn't a fork of Chromium these days. |