This statement is made as if the author thinks rendering the contemporary web is a trivial achievement.
Now, I'll admit that there is an enormously complex process required to render modern html and css properly. But there are several engines that do this rendering and are available as open source. So it is easy to render web pages... use one of these engines.
And e-readers use Android, but the technology is used with the bare minimum amount of effort.
One very obvious change is to implement scrolling one page at a time, instead of a very slow slide-show of unreadable text until it finishes scrolling several seconds later.
So, yes, it can't even display web pages well, because they don't try to modify the browser for the medium at all!