While I have always appreciated (applauded even) Joan’s efforts on behalf of mankind, I found the extreme vibrato in her voice to be not to my liking (I feel the same about Elvis Costello). But a coupla months back I picked up a few of her old albums (Farewell Angelina, Any Day Now, David’s Album, One Day At A Time, and Diamonds & Rust), and perhaps from listening to Iris DeMent so much in the past 35 years it no longer bothers me (Iris herself sings with a healthy dose of vibrato).
I would have loved to have met Joan. A bassist---Todd Phillips---I was in a band with in 1971 was playing in her road band about ten years ago, but I didn’t see them live. She’s very intelligent, and has a great sense of humour. She does the best impersonation of Dylan's speaking voice I’ve ever heard. 
Thanks for the post and link @mofimadness, I’m gonna watch it.