> your phone starts downloading a large PDF instead (4MB, what the what?).

I agree about the parent point of marking PDF as such but still feel compelled to point out that a 4 MB PDF is not significantly bigger than a lot of regular pages that are posted to HN.

In this very moment the currently highest ranked link, which is just a regular web page, on the HN front page had a total network payload of 3,937 KiB according to Google PageSpeed.

I sympathize with what you are saying though in general, and I think it is sad that so much mobile bandwidth is needed in order to read stuff.

The way that I personally get around this is that when I am on mobile I mostly restrict myself to reading HN comments instead of clicking through on any of the featured links themselves. But depending on how you like to use your phone I realize this might not be feasible to switch habit into.

Except a lot of regular pages are just pages and so it is trivial to read them at 20kb size because you obviously run your browser with extensions that block the loading of the vast majority of resources on the page until you whitelist them. A 4mb PDF is a single 4mb file. A 4mb webpage is more like 100 separate files, most of which can be entirely forbidden from loading at all, and many of which can be set to load only once tapped on (like images).

> you obviously run your browser with extensions that block the loading of the vast majority of resources on the page until you whitelist them

I think most people do not do this on mobile. Even among the HN crowd. For example, on iPhone that I use, Safari does not support extensions. So for most people on mobile the site will download everything.

iPhones handle PDFs just fine?

Ok!