[pasc1878]

This is the benefit of HTML.

The reader can alter its format e.g. change font and the result still works. (agreed that it needs to be decent HTML - but plain HTML works it is some of the complexities that make this not work and I consider that a bad HTML page)

PDF is fixed format and you can't increase font size to make it more readable.

However for some of those use cases then not being able to alter PDFs is a benefit - e.g. invoices and bank statements but then you probably need more than a plain pdf which can be edited (e.g. change a 1 to a 9) but a pdf with some integrity checks.

[pathartl]

This is a nightmare for people who produce actual print materials. My SO is a print designer doing mostly packaging design but also does some trade show materials. There is an incredible amount of thought in layout that can almost be considered branding for a company. Additionally, the static nature of print allows you to do complex layouts that wouldn't be translatable to HTML, let alone support different rendering engines, browser sizes, etc.

Many times even things like page or column breaks are extremely intentional. Having something "beneath the fold" or flowing onto another page can drastically change the way someone interacts with the piece of media. No PDF isn't great (my particular beef is with how there's almost no sense of a sentence, block, paragraph etc so it makes it almost impossible to copy or parse for text), but keep in mind that HTML/CSS only just reached near-parity in features in the past 5-6 years.

[crabmusket]

This is why I specified originally "as someone who isn't a book or magazine publisher". A bit too specific, but I meant to head off the discussion before it got to your SO, who has legitimate needs very different to my own.

I'm talking about documents which are purely valuable for their content, not for their branding, and where the reader's accessibility is more important than the creator's design.

[pasc1878]

I totally agree but the important phrase here is "produce actual print materials"

Reading on an electronic device is a different problem than providing something to be printed on a fixed format unchangeable piece of paper.

Thus you have different formats for the two different requirements. The issue is people keep trying to mix them up.