Not always. For example, if the dozens of papers are all disjointed, or on completely different topics, you can simply bolt them all together and call it a PhD

Not always. For example, if the dozens of papers are all disjointed, or on completely different topics, you can simply bolt them all together and call it a PhD thesis. Like all good stories, there has to be a solid start, middle and end. This generally also means that one fantastic paper is also not enough, content wise, to warrant the award of a PhD.