Don, I appreciate the perspective on times and places where people pretty much had to rely on oral tradition, even for sharing very sophisticated, lengthy songs, poems, etc.   And I don't think there's much disagreement here about the value of committing songs to memory and even overlearning them to the point where you could "sing them in your sleep," as it were.

Still, several types of situation have been mentioned in this thread where song sheets or even books (other than RUS) can be a real asset.   
One is group singing, where the "sing-along" parts are not short, very commonly known, or repetitive.   

Another is the situation where the performer's ability to memorize long lyric sequences and recall them without error even in the face of distractions, nerves, etc.   (And most people get over their stage fright only as they make themselves get up and perform over and over in spite of the nerves; if everyone waited to perform in public until they had overcome their performance anxiety, a lot of people would never perform.)   

Still another was just mentioned:
"At a folk club I no longer go to, the most entertaining of the regulars only ever sang from sheets. His genre was verbally intricate Victorian music hall. He could communicate them brilliantly, but rarely did the same one twice. Memorizing them wouldn't have made any sense. The whole point of his act was that it was a window into a multifarious culture of the distant past."

It's not all that unusual for someone to want to share a song that they are not likely to perform again soon, if at all.   This could be something shared for a special occasion or theme workshop.   Or it could be that the performer simply likes to present something different most of the time instead of the old standbys.   I'm not sure every one-time presentation at a music camp or singaround warrants weeks and weeks of preparation just to avoid having to glance at a lyric sheet occasionally.


"This guy certainly was [ready to perform]. Can YOU do that? Pick up something with a long, tricky, chromatic tune, wacky rhythm and complicated internal rhymes, and do it fluidly carrying off all the original jokes?"

It's been mentioned before that choirs and orchestras often use sheet music because what they are performing is complex. I've seen jazz jam sessions and even folky fiddle sessions where sheet music was used for similar reasons, with the quality of the music probably benefitting, not suffering, from the use of it.    And "poetry readings" and "dramatic readings" used to be a fairly common and respected type of entertainment.   The ability to interpret lyrics, prose, and music while 'reading' from a page is not an oxymoron.

Are most of us really disagreeing on a lot of points, or are we (in this thread) mainly switching from one subtopic to another?