That is kind of annoying. Also irritating is when people DO have co-writers, people call them the ones who "wrote the song for them". If they're listed as a co-writer, they should at least get credit for co-writing. No one can know for sure if they actually did it, but still.
On the topic of Celine Dion, I'm sure she's a great singer but I find she shows off her voice a tad too much. Christina and Mariah are also guilty of this.