alt Hacker News> Why should we aim to increase portability? There's a lot of unstated ideological assumptions underlying that goal, which not everyone shares.
As far back as I can remember well (~20 years) it was an explicitly stated goal to keep the web open. "Open" including that no single vendor controls it, neither in terms of browser vendor nor CPU vendor nor OS vendor nor anything else.
You are right that there has been tension here: Flash was very useful, once, despite being single-vendor.
But the trend has been towards openness: Microsoft abandoned ActiveX and Silverlight, Google abandoned NaCl and PNaCl, Adobe abandoned Flash, etc.
There are shades of the old GPL vs BSD debates here.
Portability and openness are opposing goals. A truly open system allows or even encourages anyone to extend it, including vendors, and including with vendor specific extensions. Maximizing the number of devices that can run something necessarily requires a strong central authority to choose and then impose a lowest common denominator: to prevent people adding their own extensions.
That's why the modern web is the most closed it's ever been. There are no plugin APIs. Browser extension APIs are the lowest power they've ever been in the web's history. The only way to meaningfully extend browsers is to build your own and then convince everyone to use it. And Google uses various techniques to ensure that whilst you can technically fork Chromium, in practice hardly anyone does. It's open source but not designed to actually be forked. Ask anyone who has tried.
So: the modern web is portable for some undocumented definition of portable because Google acts as that central authority (albeit is willing to compromise to keep Mozilla happy). The result is that all innovation happens elsewhere on more open platforms like Android or Linux. That's why exotic devices like VR headsets or AI servers run Android or Linux, not ChromeOS or WebOS.