Around ~2000 we founded a startup on knowledge management (to tag people), and we had a nice fuzzy search on ontologies implemented.

We got into large companies to solve their problem: Different ontologies in every department (E.g. engineering vs. marketing vs. sales).

Mapping didn't help because their fundamental world views were different.

We failed.

(My Wiki engine made it into Atlassian Confluence though, and Confluence users had to bear with my horrible {...} wiki macro syntax for years)