I totally disagree. The spec dies not exist. It isn't buried in your customers' brain or your CEO's. It isn't mined. It is invented, one way or another, by those making the damned thing.
The "requirement" for a spaceship is "must travel to the moon." What software requirement mining tries to do is mine Kennedy's mind for the design of the bathroom.
Also, the requirements for a spaceship are only "must travel to the moon" if your customer is a 5 year old child. The real list of requirements is way longer and includes things like "must be compatible with our existing launch infrastructure".
The key problem in obtaining the requirements is not a problem of communication (as the original article states) but in the work that needs to be done by (or with) the stakeholders to figure out the actual requirements. And I'm not talking about making the detailed spec, I'm talking about the big conceptual requirements which often after some proper analysis get a fundamental change of perspective. This is the main issue in making good products. If you simply make a spec for the requirements the stakeholders initially think they have, your success will depend on how much thought and work they have given to choosing these requirements, and often that will be lacking.