Pseudonymous recommended to me:-
There is a book that goes into this in some detail; you might enjoy it: https://www.dukeupress.edu/Segregating-Sound/
Thanks for that. I may well try to get my hands on a copy of that though I did read the description on that website that includes:-

Focusing on the late nineteenth century and the early twentieth, Miller chronicles how southern music—a fluid complex of sounds and styles in practice—was reduced to a series of distinct genres linked to particular racial and ethnic identities.

Now, this era in the early days of jazz and jazz-blues is one that I have been interested in (obsessed by?) since I was a schoolboy and the whole area of the ethnicity and racism in all aspects of commercial recordings is an area that I do know a great deal about so I feel that my reading time ought to be devoted to areas than I feel I do not know enough about.

Here is another quote from that post:-
I am not saying that the 'niche' marketing was a necessarily a bad thing, and maybe it did preserve stuff that might otherwise be lost, just that it was something that continued.
Well, if you are talking about Soul music, Reggae, South African Township, the vast, growing and fascinating number of Manding jali recordings (amongst other genres) well. yes, specialist labels continue, but there is certainly a far higher proportion of entrepreneurs, recording engineers and other record label staff that come from the ethnic groups concerned than there were in the 1920s-ish era. The most interesting part of that quotation to me is it did preserve stuff that might otherwise be lost. You are right! There are numerous examples of exploitation, missing royalties, mistreating of source singers and musicians on both sides of the Atlantic. Just mention the name of Peter Kennedy on Mudcat and see the explosion that you get! However, we need to be eternally grateful for the recorded lagacy that such offenders have left behind. It is a difficult dilemma.

Another quotation from that post that I would like to respond to is this one.
And the folklore revival was a specific 'niche' which Goldstein as far as I can see both helped to create and then fed the demand for. So I think it is fair to see Goldstein's business practices (and he had two degrees in business) as a continuation of a strategy initially developed earlier in the century.
The companies and record labels that Goldstein was producing his albums included Stinson, Folkways, Prestige and Riverside Records. His 500+ albums mainly in what might broadly (without precise definition!) be called 'Folk' and they included a wide range of ethnicity of performers. If you investigate the ethos of all those American labels in this area of music from the late 1950s onwards, you will find a close association with campaigns against segregation and in favour of racial equality.
Yes, they were commercial enterprises and yes, as you have mentioned more than once, Goldstein had degrees in and an acumen for Business. That does not in itself put him in the wrong. I have always regarded Goldstein as one of the better guys in the murky music business unless you, or anyone else, is able to point out any exploitative element in his methods. If there are, I might have to change my opinion.
There is more in what you write about the business degrees than in the vast contribution that he made. He did drift between academia and music industry, but this was a very common experience in America in the second part of the 20th century.
I'll finish this overlong post with a reference one of his great achievements, the 1963 publication of Folk Song Of The North East by Gavin Greig. Goldstein worked on this with Arthur Argo, Greig's grandson. This main element of this work is the complete texts of the weekly articles contributed to the Buchan Observer of Peterhead between Dec. 1907 and June 1911. This is one of the richest publications for folk song texts from a part of Britain that was one of the strongest surviving traditions at the time. Goldstein's business acumen must have failed him because this priceless outstanding book did not sell well. What did Goldstein do with the excess copies? He shipped them over to Scotland for the TMSA to distribute and sell at a very much reduced price. That is where my copy came from. I would have to nominate it as being one of the books that has enriched my life.