At least in U.S. folk clubs, open mikes, and song circles, the encroachment of song books and crib sheets has little or nothing to do with hymn singing in church, or religion and religious traditions.

Sad to say, it's simply a matter of laziness on the part of those who wish to participate but don't want to exert the effort to learn the songs before singing them before the whole group.

Don't make it more complicated than it is.

I've been there, I've watched new people come into the group lugging their armloads of songbooks and/or three-ring binders full of crib sheets, and then bore the crap out of the "old-timers" who always learned a song before they sang it for others. The old-timers heaved a sigh and gradually drifted away, leaving the song-readers to it--meanwhile, gathering in private homes and continuing to sing for each other. From memory.

Now, these newcomers may be somewhat influenced by church-style singing from out of a hymnal, but I really don't think that has anything to do with it.

Don Firth