I would be somewhat surprised if web to PDF can generate PDF results that are suitable for pre-press.
You would be surprised!
Despite the fact that very few things are natively supported by browsers, it has been possible to print books using CSS and HTML for several years.
You can find quite a few (mostly proprietary) implementations of the CSS Paged Media Module and CSS Generated Content for Paged Media specifications, to name a few
- PDFreactor
- PrinceXML
- Antennahouse CSS Formatter
Some tools only implement a subset of the specification:
- pdfChip
- Weasyprint
And last but not least, there's a free and open source _javascript_ library called
Paged.js that acts as a polyfill for the CSS modules to print content using features that are not yet natively supported by browsers.
A good reference is probably Dave Cramer from Hachette Book Group:
For almost ten years, Hachette Book Group, the fourth-largest trade publisher in the U.S., has been creating both print and digital books with HTML and CSS.
But as mentioned by Dan, there are a lot of other things to solve first so let's not digress too much :)
Cheers,
Guillaume