Often, the hidden agenda is considered to work in the reverse direction, with shoe companies suspected of “paying off” for favorable articles (possibly through advertising). I'm curious about the idea of a hidden agenda for discussing the idea of shoes being overrated.
Right, this is why the article in question is so interesting. It is rare to find anyone willing to speak out against a predominant paradigm. Who the heck would benefit from proving that modern running shoe design is overrated? That Emperor's New Shoes start-up?
As for scientific studies, the problem with “non-scientific studies” is that they can say whatever they want. My non-scientific study of one says I have had fewer minor issues and major injuries wearing less shoe than I have had wearing more shoe. Of course, I'm willing to say that this doesn't mean much because my one major injury in 19 years running had nothing to do with the shoes I was wearing and there could be many reasons for the fewer minor issues, the shoes being one of those many. Other such “non-scientific studes” have the same problem.
The interesting thing here is that, beyond one group of anecdotal experiments or the other, we have had input from two giant luminaries in the sport, Lydiard and Bowerman, both of whom observed many, many runners and their shoes over the years and agreed that less shoe is better.
As for people rushing to become competitive runners, it's not that they aren't competitive runners. It's that novice competitive runners want to train at intermediate and advanced competitive levels. One needs to build through the levels, many skip to advanced levels of training in certain aspects (most notably speedwork) without doing the prerequisite work required to be able to withstand the stresses of that training.
Some may not even start out as recommended to be novice runners at that point, either. Some would benefit more from taking a more patient (go figure) long-term approach that has them exclusively swimming, cycling, and walking to get weight low enough and build up a decent amount of musculoskeletal durability before throwing in the much higher impact stress of “pounding” the miles in running. But, as observed above, there is a whole industry that profits from encouraging people to go from couch to marathon ASAP. Not enough of those involved with the sport are willing to give more honest, thoughtful, measured advice — by comparison, there is no money in it!