>I wouldn't call turning browsers into application runtimes "major innovation".

I would call it one of the most important innovations of the last 20 years. Name another true write-once-run-anywhere universal VM that is installed in billions of consumer devices and costs nothing. It doesn't exist. The only way the entire modern software ecosystem is even possible is because of the web as a platform. Literally everything else is a non-portable closed proprietary stack.

I argue that such a thing as a "true write-once-run-anywhere universal VM that is installed in billions of consumer devices" is not needed in this form. It creates more problems than it solves.

> Name another true write-once-run-anywhere universal VM that is installed in billions of consumer devices and costs nothing. It doesn't exist.

Java certainly meets your criteria and exists. But much like the person you are replying to, I consider the "modern software ecosystem" to be utter garbage. Web browsers are just a terrible user experience for applications compared to the desktop. We have regressed greatly in user experience, not progressed.

>Java certainly meets your criteria and exists

It does not. Nothing about Java provides a sandboxed runtime environment.

Nor does anything about WASM. The sandbox is provided externally. The only difference is that Java standardizes functions for things like file access, while WASM doesn't standardize them (but WASI does!)

You don't need a VM for a "write once run anywhere" environment at all. That's the whole point of high level programming languages like C and Fortran. The innovation of having a VM to run everything in is to be able to compile once and run anywhere, which is only valuable to people wishing to hide the source code from the people running their software (malware authors).