It's a mass start for many thousands of riders. So there are a lot of accidents in the first few miles. I'm not sure where you would go to gain experience riding with a huge mass of inexperienced bike riders as no responsible bike club uses mass starts any more. For the Pelotonia organization the publicity of large photo/video/news worthy mass start is more important than rider safety. On the plus side, Pelotonia has a lot of EMS services available and they stay busy.
If you don't already, riding with a bike club like Columbus Outdoor Pursuits or Westerville Bike Club will gain you experience riding in groups.