As near as I can tell, the author is suggesting that you should not get Amazon Prime and/or a kindle _device_ (as opposed to a free app for a computer or mobile device) primarily for the purpose of taking advantage of the kindle owner's lending library.
Words fail. Okay, this is me. I have a few anyway.
I got Amazon Prime because I was spending more than the annual fee in a lot less than 12 months on shipping anyway (not _everything_ was available via Super Saver and besides, I'm just not that patient). On some very basic level, I feel like getting Prime for any reason other than that is silly. On the other hand, I buy a lot fewer p-books from Amazon compared to when I started Prime. At this point, Prime is self-justifying because it has caused me to switch from purchasing in person and/or on some other site to purchasing from Amazon, unless it's _really_ not available (or a substitute) from Amazon. Research suggests Prime does this to everyone (straight talk version: Prime is addictive). This is probably a solid argument for not getting Prime, for any reason whatsoever; it's classic distortion of what you would otherwise do, to a specific party's benefit (straight talk version: that would be to the _dealer's_ benefit. Junkie feels like it benefits her, but that's arguable).
Should you get Prime? Probably not. But if you should get Prime, fuck _no_ you shouldn't get it so you can borrow books through the kindle owner's lending library. Should you buy a kindle e-ink reader or a kfire? Heck if I know. But you should _definitely_ not buy one primarily to borrow books through the kindle owner's lending library.
Who would even _think_ of that? Altho the fact that people who think that way even exist is a testament to why Bezos and Amazon's marketing department are way, way better at this than I could even conceive of becoming.