It's a complicated situation from both side. If you're the company, you have to anticipate that the other candidate might get another offer, or turn you down, or turn out to be a flop, so you want to interview other candidates at the same time to have a back-up plan. And that's a good thing for the article author too, because it gives them the chance to see if they're a fit for the job and could learn the required skills even if they don't have them now. And it's great if it works out... but shitty when it doesn't.
It's worth realizing that it's a losing situation for the company, too. It's not like they want to waste a bunch of time interviewing you for a job you're ultimately not going to be in any more than you want to waste time on it. But unfortunately "wasting a bunch of time interviewing" is just how job hunting/hiring works these days.