Just think! If we had BS from the mid 19th C. (or you name the time) similar to that on Mudcat, we would have a priceless insight into the period, one that historians would ceaselessly mine for their tomes. The few diaries, letters, newspaper comments, songs, that we have from the past only dimly reflect that past. Most of what we have had been predigested and written from some pundits point of view.
Regarding the Spirituals project (and the past compilation of Western Range (Cowboy) songs, etc.), we have a difficult time understanding the people who originated the music. They were literal, largely illiterate, limited in their view of the world and yet produced something of value. We have to peruse the BS of the past (sparse as it is) in order to understand even a little of the subject.