Most of the singers that I met that have no training have one issue: they have no singing power and have a weak diaphragm. They might be perfectly in tune but they are not really belting it out.
From my experience getting to that level requires a lot of practice, every single day. But I was always told that some people have just talent and that's why they are such successful singers. Now I started to doubt this theory.
Are there really singers that can be great on a stage without any training? And are there singers that can be great on a stage without much practice? Any famous name?