The KEY is to find what works for you, your personality, and your team. To insist a particular method does not work because it did not work for YOU or because YOU don't personally like that method of prospecting - does not mean it does not work or will not work for someone else and I think you do your team a great disservice by not presenting a wide array of "methods" so they can find their particular niche of expertise.
You need to find what works for you.
I bought leads early on, I hated them. But I must say that calling those cold, mostly completely unqualified, leads was fantastic training. I developed posture very quickly. I learned to either qualify someone or weed them out fast. It was also great discipline making the calls day in and out. Tom Challen is great for teaching how to turn cold leads into valuable team members.
So while I would never do cold leads again, they do serve as a fabulous and fast training. And yes, many people have created huge and successful teams with cold leads.
As a couple of people have asked earlier in this thread: How do you generate your own leads?
It is so easy to say "you need to generate your own leads", but much harder to do it. That is one of the things Mike Dillard's course covers. How to generate leads via your nerve center.
It takes time and effort to set yourself up so you can generate leads. However, as you learn those skills you are making yourself a more valuable leader. The key is don't let setting yourself up so you can generate your own leads derail your building your business now. It is in this gap time that I believe cold leads - with training about how to talk to them - serves a useful function.