A bunch of great authors would not guarantee a great book, working together in writing is hard. You may have different ideas in what should be written. And five people can't sit around writing together, how would everyone get their point across? Authors can have shy personalities so I'm sure someone would be left out.
Actually two of my favorite authors have gotten together to write a book! (KA Applegate and Michael Grant) but I'm scared to read it because when I read both of their series (Animorphs and Gone) all of my favorite characters died.
i forgot the title but i read it like a year ago im not exactly sure how it ended but im 90% sure none of the good guys died but dont quote me on that it wasnt like OMG BEST BOOK EVERRR but it was good. I think.
Rowlimg: avada kedavra