The point of the article is that the first problem is not so much a problem and more of an afterthought compared to the more fundamental issues of spacing, proportion, weight, characters per line, and placement on the page, which all equal readability. Once you have considered those, you can more or less drop in whatever typeface you like and then ask yourself whether it improves or detracts from readability and whether it matches the overall tone you are trying to set with your design.