Melodyne has become a victim of it's own brilliance. It has a great reputation, which creates hype, and leads many
to assume Melodyne "promises" to do things that no software can do. We've seen similar behaviour with some, say, software that promise to remove vocals from a commercial release. They may work quite well with some particular songs, depending on the arrangement, and be a complete failure with another, because impossible is impossible.
When you combine that with unwillingness to spend hours on seriouysly studying the software, you get a disappointed user
who blames the product.