You should note that this article concerns only the US and other “rich” countries. $100 per a small illustration is quite a bit if you live in the East. I have to earn around $800 per month to live quite comfortably (~8 days of work).
I usually work for small indie companies or individuals trying to break-through with their games or whatnot, so they are very happy with my pricing. If I do a decent job, I get a lot of love and respect in return, not to mention free reign over the art direction. I have never been treated badly in a $100 job.
But I absolutely agree that if you’re not good enough to produce amazing results, you should concentrate on practice until you can. I have seen so many artists charging hundreds of dollars for their shitty illustrations, maybe those are the ones below poverty line:)