So many complaints about web technology, where is the replacement? I'd be interested to know if there was the one true layout system that everyone agrees on
TeX [0] is in some sense "the one true layout system", but it's designed for printed documents, so it doesn't work on the web [1]. And in some ways, it's much simpler than CSS (you can build nearly everything from only a dozen typesetting primitives or so), but in other ways it's much more complex (since TeX is itself a fairly complex programming language). It's typesetting quality is still unbeaten by any of its competitors though, even 50 years after its first release.
My understanding is that it's designed for fixed-size documents? There's a big difference between a layout system for that, and one where size of a document can vary wildly, up to completely opposite aspect ratios
I guess I'd call it mostly fixed: most TeX engines only produce a single page size at a time, but you generally only need to modify a single variable to change the page size and, after recompiling the document should be perfectly reflowed into the new page size. This is not helpful at all for someone who wants to be able to freely rotate their phone, but it's still better than InDesign or Word where changing the page size will probably break the layout.
There is actually a TeX extension that supports viewers arbitrarily changing the page size of documents [0], but it's fairly new, and as far as I'm aware it has essentially zero adoption.
The web is probably the closest thing the software industry has to a truly universal, open application platform.
There is corporate influence, but it is substantially more vendor-neutral than any other UI platforms.
The web stuff mostly uses licenses such as MIT, Apache 2.0, and BSD. GPL-licensed projects exist, but still many more on permissive side.
Web is based on open standards developed through organizations and specifications are publicly available, royalty-free, and implemented by multiple independent browser engines rather than being owned by a single corporation.
I remember that there were these talks called "Linux sucks" (IIRC) and the premise wasn't that we should start using Windows but more like "we can do better and improve it." Not every complaint needs to come with a solution or better alternative.
The complaints shouldn't require a replacement at least in the web's case the replacement is still the web standard, a better, iterated version. It's a living standard and criticism keeps the platform slowly but surely evolving. I think it's a healthy feedback loop.
Not which works under the same constraints as the web.
But for simpler scenarios (like fixed-sized paper, desktop displays before super-wide screens), you can have both simpler and more precise layout systems.
[0]: https://en.wikipedia.org/wiki/TeX
[1]: But it does work on WEB :) [2]
[2]: https://en.wikipedia.org/wiki/Web_(programming_system)