Alan Kay, on Quora, about Web Browsers as document viewers
Again, I was not a big fan of Alan Kay but he definitely nailed this one.
The original idea was to instigate as much progress as possible without incurring lock-in to a huge OS, but to protect what needed to be protected and ensure a threshold of system integrity and reliability.
One way to look at where things are today is that the circumstances of the Internet forced the web browsers to be more and more like operating systems, but without the design and the look-aheads that are needed.
Basically, web browsers were bound to become OS. However, Alan Kay tried his best at the time (90s) to make sure that the "Internet-OS" was designed correctly.
So what you really need is an OS-like system/software/VM facing the Internet whose main responsibility is security. After that, it should provide access to low level primitives (e.g Graphics, etc.).
The underlying system for a browser should not be that of an “app” but of an Operating System whose job would be to protectively and safely run encapsulated systems (i.e. “real objects”) gotten from the web. It should be the way that web content could be open-ended, and not tied to functional subsets in the browser.
As with any decent OS, it has to allow for new ideas while also providing the resources for safety, efficiency, and to manifest user experiences.
Alan Kay also argues that sending programs (rather than data structure) is an extremely good idea (based on his experience with JAM – later became PostScript).
This idea of having an OS to exchange programs created by others and being able to author them reminds me of Pico8.
He also talks about Locus by Gerry Popek:
Perhaps the best early structuring and next stage design of Unix was Locus by Gerry Popek and his researchers at UCLA in the early 80s. [..] It was easy to see that combining this with an end-user language would provide a network-wide system that would run compatibly over the entire Internet.