I know quite well what makes LilyPond stand apart and the perfect choice – from my point of view. But when following (or participating in) discussions in the community one notices that there are many different point of views, that use cases vary widely. People love LilyPond for very different reasons, and people struggle with LilyPond for very different reasons, maybe even because it isn’t the perfect choice for what they need to achieve.
While I have some ideas about what others could like about LilyPond these are actually just guesses – probably not even educated ones. So here is the opportunity to shape the picture a little bit: