I don't understand why these should be mutually exclusive. Starting from a common parseable markup you can have both responsive HTML for browsers and formatted PDF for print. Why don't decouple content from presentation?
If the HTML is responsive, why can't it be good for print? And, for the sake of reducing waste, should we not discourage people from printing in the first place?
You'd probably want a dedicated print CSS to remove various bits of UI and decoration, as well as styling which works well on a screen but is terrible in print (e.g. the white-on-black and white-on-blue headers).
However gov.uk already does both so it's not an actual issue here.
Having hard pagination and consisstent layout is, for me, a cognitive gain, esspeciially for longer documents, say, 20+ pages. (I frequently read 500+ page docs.)
Other formats such as ePub are frequntly compact in space utiisaation, but again, the free-flowing text lacks the mnemonic framing of even a basic print book, let alone the expertise of a masterpiece of layout & typography such as Tufte.
Not that HTML isn't well-suited to other cases, or that PDFs can't be awful. But there's a place.
