Virtually any professional in any discipline would agree, that they learned far more in their first months on the job then they ever did while studying in school. Just by entering a peer group of people doing what you trained to do teaches you that there is more than one way to tackle a given problem, that your way might not be the best/most efficient way, and you adjust as you gain new tools from your peers to add to the skillset you came in with. By that same token, your peers are learning from how you approach things as well. Everyone gains.
In blogging, there is no shoulder to look over, showing you how they approach a task. No one to call over to look at your work and give you feedback. The very solitary nature of running a blog means that most people are re-inventing the wheel every time they have a problem they don't have an answer for.
The workshop's purpose is for people to be able to work in the same space, feeding off each other's creative energy, offering constructive criticism where it is needed, and figure out better ways to tackle the blogging beast in a way that makes you happy and fulfilled.