The short, blunt answer is that it is a buzzword/fad/gimmick.

"Knowledge Management" is attractive to managers who really want to believe that they can “manage knowledge” without regard to knowledgeable and experienced people.

This is no different than other ideas like “Total Quality Management” or the “ISO9000 Quality Management System”.

Notice the word management is the key to all these. They are designed to appeal to and be sold to managers. They are not quality systems or knowledge systems, they are management systems.

On the other hand, when a bunch of people get together and share their experience, good stuff happens. Simple. Too simple to make any money off of as a consultant or auditor.