While I personally dislike people singing from books, that's not the main problem with the folks that use RUS. The "Blue Book" has somehow gained the status of being an authority as well as being a crutch. I've attended (once each)sings where book-wielding participants would angrily proclaim "you're singing it wrong!"; I've seen people who insisted on announcing the page number for songs like "I've been working on the railroad", and people, who, when asked what key they wanted an accompianist to play in, looked it up in the book. I've seen several good singing groups effectively ruined by overuse of RUS; I've never seen one that was improved by it.