burkek
PDFs are generally not accessible (unless specifically made so), don't re-flow on a mobile device with a small screen, and sometimes require a third-party viewer just to see them. Definitely a no-brainer to discontinue the format.
KEv
Actually you really don't need a reader at all, which is a good thing because I’m not a fan of Acrobat. Google and Chrome include efficient built-in readers, the Mac’s Preview app reads PDFs, Linux distributions come with a PDF reader like Evince, iPhones and iPads have built-in PDF support, and of course Android has a built-in PDF viewer.
Before deciding to use the PDF format, I tested on iPhone, iPad, Android phone, Mac and Windows desktops and laptops, and with third-party PDF viewers (e.g., Foxit), as well as the one from Adobe. Everything loaded exactly as it was supposed to and scaled appropriately to the screen size. I used 12 point instead of 10 or 9 point fonts to make the eZine readable on small screens. I also verified that the content inside the PDF was discoverable by Google.
I felt it was important for the eZine to have production values - text flow around images, no widows, appropriate page breaks and line spacings, plenty of graphics, etc. The PDF format preserved all the page layout elements perfectly on all the devices tested above. My assumption was that most people would read it on a mobile device, on a desktop, or download into something like an iPad. The PDF accommodated all of those options while preserving the layout, and had the benefit of global universality.
FWIW in all the threads commenting on eZine articles or on the eZine itself, there was never a comment that the PDF format was unsuitable for any reason. I don't think anyone expected it to be an eBook formatted for something like the Kindle.