Interesting discussion, thanks for having it.

I think we misstate the problem when we cast it in terms of "profesisonalism" or by compiling lists of celebs who do and don't use cheat sheets. The real question, IMHO, is to what extent (if any) cheat sheets undermine listener experience.

Imagine a stand up comic reading her lines, or a joke party where folks are reading their contributions from a book. I suspect this would knock a good 30% of our experience as listeners. Why might we think it is different with singing?

Memorizing the song is not always feasible and it is almost never easy. But it tells the audience that we love the music and them enough to do so.

There is a cost in using cheat sheets. And although sometimes it may be worth paying, we do well to recognize that it is not always so.