no idea what your trying to say here....why wasent Whitney a great singer? she had range, she had originality, what was missing?
as far as Dylan (and again, I am a huge Bob fan, have seen him live several times, and religiously listen to recordings/records), we obviously have a different interpretation of "great singers"...he is a great songwriter and as someone pointed out in previous post, has found a voice for his song writing...but the man cant sing (self admittedly, see last rolling stone issue interview with him) a lick...sure he has one of the most recognizable singing voices of all time, but he wasent a great singer (in the sense of being able to carry a tune and/or has no range) - so if your trying to say his voice matches his music, then sure I agree...
I would label great singers as people like: Sinatra, Robert Plant, Adele, Mercury, Etta James - people who could sing almost any song and have it sound beautiful...
just my two cents though