Basically, the GDP lets people/countries cheat - since it's "Gross" it doesn't have to report benefits in a "net versus gross profits" kind of way. But that's not how any business would be able to operate - you have to factor in your overhead, cost of labor, etc, to be valid in terms of reporting your revenue and profits. But that wasn't how the GDP was built. So....it's time to lose the GDP in favor of something better.
The GPI is being used in Maryland, Vermont, and soon (potentially) in places like Seattle. If it become a standard measure, companies as well as states will have to incorporate its metrics moving forward. Exciting stuff.