The problem with it really is as the author suggests the lack of authentic experience on the one hand, but I think more importantly it's that the idea of "mental models" just tries to hand people a bag of disjointed tools.
When you look at what it means to really understand something and you look at say a world class pianist or something, then you'll almost certainly find they have an integrated perspective on what they do. They don't have model A and model B and model C and a bag of fortune cookie wisdoms, they have tacit knowledge and beliefs that are coherent and whole. Really understanding something ironically often leads to the inability to articulate how it is one understands it, because it's just become integrated into how someone operates in general.
Umberto Eco once made the great point that unread books are much more important than read books because known knowledge pales in the face of everything that is unknown, no matter how dedicated one is to reading. And it's the same thing with these mental models. You're not smarter because you know 200 models or 300 models or 400 models, just like reading 50 more books per year isn't going to make anyone any smarter in a sort of simple additive way.