In addition PDF adapts, by design, a model of paper to the web. It's a "horseless carriage" file format.
Font size, page width, cut/paste and presentation in general should be the reader's choice, not the writer's. The Web manages this, sort of.
The OP is right on in this regard. Even the TeXs of this world, while better than the binary formats, have upgrade complexity.
Sometimes. There are a lot more design options available if the creator of the content maintains control over layout, fonts, etc. Sometimes this doesn't matter--if it's a block of text for example. Fairly simple layouts also render pretty well on the web.
Different content works better or worse with different approaches. One isn't intrinsically superior.
They are OK in theory, for the reasons you state.
The problem is the gratuitous use of PDF which we have all experienced - here's a common (pathological) example:
Document author starts with plain text - no special formatting or fonts, no images, etc. Somehow their toolchain converts that into a PDF file that contains No text, but rather an image of text.
The result is a big, bloated, unnecessary use of PDF that cannot even be parsed or used with anything but a graphical PDF viewer since the text is now gone - there is nothing but a picture. Of text.
PDFs are awful.
Could have stopped right there.The spec is 1000+ pages, references other docs, has many omissions and contains much that is apocryphal, or at least wildly inaccurate
right now, today, tuesday june 13th, 2017, safari will not open a .pdf to a specific page or bookmark, neither on the desktop nor in ios.
chrome can. firefox can. but safari cannot. which means neither the iphone nor the ipad can do it.
imagine if -- on the web -- you couldn't deep-link to an anchor in the middle of a webpage, but merely to (the top of) the webpage itself.
that's not the only deficiency of the .pdf format. it's not even the most galling one. it's just the one that happens to be hamstringing a certain project of mine at the moment. and it's illustrative.
Kindles etc. are great when you're mostly reading a flow of text. For anything that benefits from design layout -- positioned graphics, sidebars, footnotes, etc. PDF on a 10" tablet is often better.
Technically, it could be anything. The layout is specified, and everything stems from this.