And wait a minute, are they saying their other conventional running shoes don't strengthen the foot and ankle? Well, if they don't strengthen the foot and ankle, they must be atrophying the foot and ankle, and right there would be a sue-able offense.
If a product that causes weakness can be proved to be damaging it surely stands a good chance of being the subject of a successful law suit, unless there are substantial benefits. In my view that has to be the case; how would a skin cream that makes skin permeable to viruses, or a supplement that makes bones porous be judged in a 'health and Saftey' context? To withstand such a suite, the benefits would have to be proved to outway the negative aspects. For instance, steroidal medicines have a whole array of nasty contraindications, but they are often needed.
How about the manufacturers and prescribers of orthotics? Those companies/individuals can no doubt claim that without such intervention, patients' existing conditions would not have been treated effectively. I think that to break that defence we need well designed longitudinal studies that demonstrate biomechanical strengthening to be more effective at alleviating/preventing injury than simply shoring up weakness. Common sense says that in most cases this MUST be the case, but do those studies exist, and are they being conducted?