Except that you rendered to Postscript--which is a general, stack based programming language (with a bunch of domain specific font manipulation code baked into it as well).
Thus demonstrating my point that the moment you go above a VT100 in presentation quality, your complexity goes exponential.
The point is that the same markup source produces different output endpoints depending on the device and capabilities available. Straight ASCII text, possibly with ANSI sequences, for a terminal. Fully typeset output for a raster display or printer.
What you're raising as an objection is actually the entire point of my example.
The complexity of the markup isn't relevant. The complexity of the renderer is.
And you are grossly underestimating the complexity of even an ASCII typesetting engine. RUNOFF/nroff/troff/ditroff/groff isn't even easy for a character device like a vt100. The developers of those engines reads like a who's who of computing luminaries.
My point as to why rewriting a web browser is hard is that you are developing a "typesetting engine", and developing a typesetting engine is HARD.
Thus demonstrating my point that the moment you go above a VT100 in presentation quality, your complexity goes exponential.