It is not unlike a French thinker advertising the superiority of French thought amid the surrounding Anglo-American world. Or, for that matter, like a French jazz musician talking about how the Americans think they own all the licks. Below the genius level, we all tend to resemble one another. Some were more creative than others. Whether they were also lighter or darker is less important.
Jazz now crosses borders all the time.
Passports are no longer required. Thousands of ways. Looking at it from today's point of view, the musicians Sudhalter writes about are far away from any definition of anything resembling the cutting edge. Their influence has long since been assimilated. Consequently, the subject is of secondary interest.