Indeed you could write an order of magnitude simpler browser, and also write the web pages it could render. Probably most people wouldn't bother using it since

Indeed you could write an order of magnitude simpler browser, and also write the web pages it could render. Probably most people wouldn't bother using it since they want to read some other, legacy web pages (you know, to pay their bills, shop online, check the weather forecast, book their flights). The analogy with operating systems is not silly, actually. Operating systems have indeed benefited/suffered from the network effect caused by "content" (programs). OSs were indeed becoming also feature-rich bahemoats that are hard to recreate faithfully enough in order to run that legacy stuff.