I do agree. People believe VR has failed again and again, but actually it's quite successful in various niches and the experience it provides in those niches is irreplaceable by other technology.
The needs and desires of those niches are pretty well understood, but what I think the market considers a failure is actually the local optima of the current state of the technology.
What Apple wants to discover is what everyday people, their customers, your typical iPhone holder, what do they tolerate and what will they do with VR?
The mass market is not sim racing, working on helicopters with AR assistance, or designing products in 3D space. They are chatting with mates, watching TV, using various life admin apps etc, none of which are improved by VR. So what does it take to get a mass market VR device popular? It's probably improving the way people achieve their daily tasks they currently use their phone for.
But is that even worthwhile? Do I actually need my banking app or chats in AR/VR? Probably not, so outside of niche entertainment I don't ever see VR being a mass market device. AR in a trendy pair of glasses maybe, people strapped into headsets all day I just don't see.