Yeah, I have no idea why Rebol and Red aren't more popular. ( https://www.red-lang.org/ ) They pack such a bang for the buck it's almost embarrassing for other language/runtimes.
Rebol itself is practically dead, no new release in a decade. It was also proprietary early on and a "weird" language (interesting, and good, but non-standard in so many ways that it was very niche). That killed its potential in the late 90s and early 00s when everyone was moving to open source scripting languages that filled the same niche, but with more conventional syntaxes and free access.
That's why it isn't more popular. In some ways it was a few years too early (to hit the zeitgeist around DSLs), but it was also a few years too late for its proprietary model.
And something else that needs to be said specifically about the Red programming language. I like the full-stack concept, ease of use, cross-compiling, and the goals they are shooting for. But, the lead developers need to get it moving. Like a small fire needs to be lit under the butt, as the competition isn't standing still.
The last stable release has been stuck at 0.6.4 since 2018. I know the lead developers have recent automated builds (December 2021), but come on, such is not going to inspire faith in casuals to join the bandwagon nor keep getting mentioned by the media. Many users like to see newer stable releases, until the project achieves its stated goals. A lot is to be said for maintaining momentum and enthusiasm.
That's another aspect of the hurdles for the newer programming languages, it's harder than ever to keep people's attention and whip up excitement.
The problem is that there are so many new languages that it's hard for any of them to gain enough momentum to encourage enough programmers or businesses to learn or even look at them. Not to mention that various top 10 languages are supported by huge companies that may rather snuff out or at least throw shade on up and coming languages that threaten their interests.
The development pace of many of the new languages is relatively slow, despite having some great ideas, syntax, or features. Which means years before they have a large enough ecosystem and libraries, to even come near to mounting a challenge to the more established languages.
For instance, another new one out there that I like is VLang (https://github.com/vlang/v). Like Red, it needs to find a sweet spot that will propel it to greater usage and recognition. Partly that can be cross-compiling and cross-platform application development. Also, strong emphasis on mobile development for both Android and iOS would help, but Apple makes their part of it difficult. To stand out, it means having easy to create UIs, their own IDEs (to maximize language features), updated documentation (to help beginners), books about it, etc... Just being on Visual Studio Code, with a hundred other languages, makes it hard to get noticed.
Compare Red with established heavyweights like C#, Python, JavaScript, or even contenders like Delphi/Object Pascal. Not so easy to pull attention away from those languages and the thousands of projects using them, unless something very compelling can be shown or proven.
> Yeah, I have no idea why Rebol and Red aren't more popular
Rebol died (for all intents and purposes) because it stayed proprietary without a large enough proprietary market too long, and good enough open source languages took the niches it could have had and built out robust ecosystems that it never developed.
Red has been disadvantaged by the ecosystem consideration, and hasn't found a killer focus that gets people over that in enough mass. They tried chasing crypto for that...
That's why it isn't more popular. In some ways it was a few years too early (to hit the zeitgeist around DSLs), but it was also a few years too late for its proprietary model.