Worth noting that Flash did succeed: It was widely used across the web and installed by enough web users that sites could usually assume it was available (though it was considerate to provide fallback content) - that even though it needed a separate installation step!
It took a conscious effort by browser vendors and Adobe to kill it and replace it with other technologies. Maybe for good reasons, but it was definitely not a "free market" development.
I also find the list a bit weird and even hypocritical in places, as, like you say, HTML itself doesn't pass all criteria.
I'd also question other points for the general usefulness as an alternative: Why does an alternative tech necessarily have to accept input from everyone? Not even open source projects do that.
Also, why does it have to be content-neutral and have to support any kind of application? Pre-web technologies generally were "host neutral" - they let you connect to any host that supported the protocol - but the protocol usually had very well-defined application semantics. It seems instead of trying to "boil the ocean", a better way would be to focus on specific domains that could benefit from alternative technologies the most.
Be device and media-neutral: Just to note, Apple only allows single-purpose apps and points to Safari for everything else. They literally forbid anyone from trying to promote any "alternative web" unless they have a say in it.
(Not quite sure about the Play Store right now, but they likely do something similar)
So taken strictly, thay point would be a nonstarter unless you already have connection to the higher-ups of current Big Tech companies.