Another Weird "Quasi" Question About Singers

Okay, this one is going to need some explanation. so stay with me, please?

When I play and sing with my guitar, I have to consciously be mindful of the key I am in and I never let my voice “let loose”.

Okay, when I’ve been drunk maybe…

So who do y’all know that can really have … “perfect pitch”? and can really "let loose?

David Clayton Thomas?

Mark Lindsay?

James Brown?

I know this must sound like such a sophomoric question, and I apologize, but in my experience as a musician, (drummer mostly) I have always appreciated anyone who can sing without accompaniment.

Does that make sense?

Thanks

Quasi