Sadly, the letter is unreadable on Firefox Android. It's like everything is a widget these days, web pages are no longer self-contained, and usability, among other things, suffers.
Hear hear, I dont understand why people do it either, it just seems like all it adds is pagination and embedding for their pdf document which already has readers custom built for the task?
If you want to make something for presentation on the web dont make a pdf.
"PDF is excellent for presenting information on the web"
Except when you want to link to somewhere in the middle of it, or view it on a resource-constrained device, or reflow the text to a window size of your own choosing, or or or...
You can actually embed fragment identifiers inside PDFs, but I don't know if any web browsers can understand them. Your other points are of course known to everybody - I even know these things myself, and yet I maintain that "PDF is excellent for presenting information on the web". Especially PDFs designed for delivery on the web, rather than 20 MB files designed for printing. HTML solves problems, like reflow, that are unsolved by PDF, but PDF is still the best choice if precise control over typography and layout are needed, as they are for some documents. The article you link to was right on target in 2003, when it appeared, but is obsolete now. Browsers no longer crash when asked to render a PDF; no external readers are needed, if you use the right browser. In Chrome I can navigate into and out of PDF documents completely seemlessly; if used carefully they can be an integral part of the web.
Yes, and no; because once upon a time (when the decision was made) it was really painful to hit a PDF, because you'd wake the memory-hogging, task-bar infesting beast that Firefox wanted to open PDFs with.
For what it's worth, the stock browser on the nexus 7 is chrome (unless you root and sideload the actual stock aosp browser or use a custom Rom with it).
The browser on a Nexus 7 when an app requests a webview is WebKit 534.30.
Chrome 27.0.1452.90 on Android 4.2.2 is WebKit 537.36.
Appears there are two 'stock' browsers, no rooting or sideloading necessary.
I'm aware WebViews are not part of Chome, since they're part of AOSP. However, WebView isn't very helpful though unless one is planning on making their own app. An end user cannot launch a WebView activity themselves past apps that take advantage of them. In short, it's an html/js rendering engine, not a browser.