I have never used sheets (yet!) but have nowt against them in principle. Particularly if, like the opening poster, you are prone to memory loss. However, there is a host of difference between singing from a sheet (or book or eReader) and using one as a prompt. You really need to learn and know the song and then, once you know it, learn to use a prompt unobtrusively. Professionals often use autocue, which is beyond the means of most of us, but there is no reason why anyone cannot have a prompt of some sort. As long as it does not get in the way of the performance or interfere with audience interaction.

As mentioned before, there is nothing worse than someone who has no idea what they are going to sing and has not prepared or rehearsed anything then leafing through a binder of random scriblings until they find something that they vaguely know. That is a world apart from someone like the openining poster who has had years of singing without a prompt then learning to use an aide de memoire correctly.

In my opinion of course!