You can find a "hello world" here: https://wiki.contextgarden.net/Document_layout_and_layers/Tu...
LaTeX != TeX. If this were a LaTeX thread, then I would agree with your point that it would make less sense to bring up ConTeXt (although someone always mentions Typst in every LaTeX thread, which is essentially the same thing). But this is a thread about TeX Live, which includes ConTeXt (and a dozen other TeX formats and engines), so it seems completely fair to mention it here.
The entire point of ConTeXt is that it is different from (and incompatible with) LaTeX. So for users who like parts of LaTeX (its output quality, its math typesetting, its underlying box model) but dislike other parts (slow speed, package conflicts, confusing setup macros, not very modern), ConTeXt is often a good alternative. But most users have never even heard of it before, which is why I appreciate Dave mentioning it in discussions like these.
I personally think that LaTeX is the best choice for typical users [0], but HN readers are seldom typical, and are often the types of users whom I think would appreciate ConTeXt.
> you could've just dropped the mic with "Ubuntu can accomplish much of what Windows and its packages can do" back in 2010, or with "Windows RT can do can accomplish much of what Windows can do" back in 2012, etc.
Well I used to use Windows RT exclusively (and am still fond of it), now use Linux exclusively, and prefer ConTeXt over the other TeX formats, so all of these seem like good arguments to me :).
