Yeah, arguments that using an ereader running Linux is equivalent to using a typical distribution of Linux from the user's perspective are specious --- along the lines of arguing that Tron is the most widely-used operating system in the world since it's typically used in automotive control and fuel systems:
http://www.linuxinsider.com/story/31855.html
William
(who really wishes it were easier to get Tron to run on a desktop, or better still a portable / tablet)