"Your tolerance level seems to be set at -100."
I think it is as unjust and irrational to describe those of us who find the use of crib sheets inrusive, as being intolerant, as it would be for us to describe those who use them as lazy bastards who can't be bothered.
I'm happy to accept Janie's argument, to a degree, but the 'Linus blanket argument just doesn't work for me at all - unless you have a deficiancy which prevents you from doing so, there is nothing to stop you putting in the necessary work in order to prepare the song for performance.
Genie;
"Just as a skilled speaker or TV journalist...."
Don't accept the analogy at all. A song is a structured piece of work with a set sequence which can (has to be) be learned; a talk is a totally different matter.
Still can't see how glancing down at a script enables a singer maintain eye-contact; it seems to me a singer is dividing his/her attention into three directions; song-script-audience; and if he/she is using accompaniment - that way leads to madness.   
Jim Carroll