it's a different toolchain, with different end-users in mind. but you have an underlying engine that arranges text with arbitrary modifications to font styles in arbitrary regions.
the kind of differences i see are at the level of whether those regions are rectangular or not (which css3 is addressing, i think). that is not critical for most use.
The TeX environment nowadays has hundreds of specialized packages which provide micro-typography support, programmatic diagrams, advanced mathematical features, detailed cross-referencing, multilanguage support, advanced treatment of fonts including ligatures, linebreaking, justification, character protrusion, grayscale balancing... A cursory glance at the PDFTeX author's thesis work may give an idea of how far the system has evolved:
http://www.pragma-ade.com/pdftex/thesis.pdf
It is impossible for me to adequately convey the TeX ecosystem in a comment -- you may consider that my question is aimed at people already familiar with it.
Now, I understand that current web technology seems to be improving to the point where, as you say, "you have an underlying engine that arranges text with arbitrary modifications..." So, I am left with the question of whether the TeX ecosystem can somehow be ported completely to create, say, HTML5 documents or something like this, instead of the current PDF output. I am talking about something new - this will not be a PDF, and it will not be a traditional webpage with features such as re-flow or "multi-browser support"... this would be an electronic publication where the author has complete control over the viewing experience. The advantage of this would be the possibility of extending TeX even further, to allow for programmatic control of the reading experience, to include features such as folding, nonlinear document structure, embedded media and code, and many other things I can't even fathom. If the current toolchain does in fact have the capabilities for TeX to be implemented in it - then it would be very interesting to create a plan for how to accomplish this goal in the proper way.
you seem to be asking two things.
(1) - can browsers support an ecosystem that matches what is available to tex?
(2) - can tex be used to replace web pages?
the answer to (1) is yes. browsers can be "programmed" with javascript to modify layout, just as mathjax does. for example, you could write a java package that formats text for printing by adding page numbers etc. this requires someone to write the high level logic, but the underlying layout engine already exists. you would also need a package system - something like what is being developed (requirejs etc).
the quality of existing results is largely a function of market, maturity, and expectations. you're comparing books (largely paid with existing toolchains) against web pages (largely free, all this is pretty new). the layout engine itself is, as i have already said, pretty much equivalent.
(2) is a confused mess that you don't seem to have thought out properly. and given the tone of your other replies i sure ain't going to help you.
On the other hand, the web technologies, including javascript, can theoretically be programmed to respond to such instructions and recreate the same kind of control we get with PDFs, and even go beyond it.
What I wonder is: if we want this kind of inter-operability, what is the crux of the matter? Where precisely does the mapping have to be made?
Thanks for your 2 cents, I "ain't" asking for your "help".
