So it works well with some songs, and doesn't with others. Nothing for anyone to argue with in t hat, so why argue about it.

Considering why it works when it does, now that is an interesting enough topic. It's a tried and tested technique in all kinds of narrative, an ending which escoes, sometimes repeats the first words of the piece in question. Finnegan's Wake, the novel, for example. I've never heard anyone doing it with Finnegan's Wake, the song, but it'd make sense enough - it'd take you back to the beginning, but a beginning seen in a slightly different way, because of how the story worked out. With a familiar story that's less effective than with a newly heard one, but even so it can be effective enough.

One reason of course why a singer might do this is because that's the way they learnt it from someone they respect. Which is a very good reason indeed.