FolkieDave,if you read the whole article Peter Kennedy appears to have ,known of Bob Blakes existence and had some inkling he was not a traditional singer,so his judgement and his decision not to record him was not made on merit.
Thankfully Mike Yates recorded him,
How many other fine singers have been lost,through the application of categories, by collectors, as a definition whether to record someone, rather than using the definition of merit.