Earlier quoted context omitted.
> Instead of developing quarto, one could have simply written a LaTeX class that defines a function like so: If it's so simple, why isn't there QuarTeX that does all of that and removes the extreme verbosity barrier?
Because doing something like this is opinionated. The LaTeX developers try to do the opposite: they want to provide packages that cover as many usecases as possible. And users of LaTeX are probably not knowledgeable enough or too busy to publish their opinionated subset of LaTeX as a class. I don't know for sure. There is no central body that has an interest in removing barriers, so you might as well ask me or yourse…
How would this macro exclude the coverage of other use cases? The language primitives would still be there to do the original code
> There is no central body
That's true for plenty of other syntaxes that at the same time aren't like this