I would rather see someone make the effort and the odd mistake than to suffer the setting up of a music stand and rifling through pages of written words.
We used to have a system of fines in a club I was involved with which included a fine of 20p if you used a music stand or crib sheet.
The worst I ever saw was at a small concert in aid of a local charity where one "Performer" annonuced he would sing one of his own songs and then proceeded to search his vast portfolio for the words of his own song.
I think every effort should be made to learn a song.music before public performance