All of what you say made sense for me...
But listen Anderson singing " deep river"or any other spirituals...
And dont say to me that she will not be able to sing anything if she wanted to...😊
And i love Joan Baez for the same reason you reject it... in any genre i listen the artist specific voice not the genre ... I dont listen many folk singer...But Baez among few others i did because she add something unique...As for Dylan...
But most actual folk singers dont appeal much to me... Some do as Dylan and Baez for example... I prefer 19 and 18 century English folk music ...
https://www.youtube.com/watch?v=2bytFrsL4_4&list=PLXa3P16r0_ytEKZJJzXxmNCV_vuQ4TiHg
English 19 century folk music ;
https://www.youtube.com/watch?v=RrXCVJOwil8
I like Russian folk music too ...As much as i like Cohen the Canadian poet brother of Dylan :
https://www.youtube.com/watch?v=TYHPEz-9sCM&list=OLAK5uy_l9_lnnIMYoEqt0XXjoHw6E4t1XAtDcsXY
https://www.youtube.com/watch?v=ktGgPkmW-A0&list=OLAK5uy_l9_lnnIMYoEqt0XXjoHw6E4t1XAtDcsXY&index=2
But it is always a specific singer i listen to not to a genre or to some culture...
I listen even to some specific Thibetan folk singer 😊
https://www.youtube.com/watch?v=WyutcSi0Rx8
https://www.youtube.com/watch?v=SvEXnSpQ220
But i dont listen folk genre in general as a genre...
Each singer is unique...That is what matter for me...
A matter of taste, surely.
How many Jazz fans enjoy Jazz sung with a classical vibrato?
Sarah Vaughan is perhaps the most "operatic" of Jazz singers but she still doesn’t sound like an opera singer.
I’ve never enjoyed Joan Baez or more recently, Rhiannon Giddens, precisely due to their vibrato. Giddens trained as an opera singer -- not sure where Baez acquired it, but to my ear, at least, it sounds very out of place in the Folk genre.
Perhaps I’m biased towards preserving a certain integrity when it comes to musical genres. No doubt, there are others who are all for breaking down the characteristics that traditionally define genres and fusing them into something new.
I can’t imagine classical guitar played with a Blues-style vibrato, for example but perhaps there are those who would find it appealing.
More to the OP’s point, as music is a language that operates on multiple levels, simultaneously, I don’t find it surprising that we may be strongly affected by a certain piece without necessarily being able to discern why or, that we may not be able to even name the particular/combination of emotions, it evokes.
A composer (presumably) is intimately familiar with how various factors such as time signature, key, intervals, timbre, dissonance/consonance, density, etc. are likely to impact a listener. As to why-- well, that’s a more difficult question.