No, you'd have some overpopulated waters with more 8 and 9 inch crappies than you could handle, because everyone would be releasing fish. There is a journal article that was done specifically on Delaware Reservoir right here in Central Ohio. The title is: Evaluation of a 254-mm Minimum Length Limit on Crappies in Delaware Reservoir, Ohio. (254 mm = 10in.) It was published in the North American Journal of Fisheries Management in 1999. This article actually overviews what happened when a 10" lenght limit was placed on Delaware. Remember, prey availability plays a large role with crappie growth, releasing a lot of fish is often not as beneficial as one might think.
As for keeping all of the fish, yea, it's not always great to see stringers like that being taken out of a system, but at the same time we don't know the specifics and the reasons they kept them. Look in my gallery, you will find huge stringers of crappie and piles of ice fishing gills. Those are the only fish that I keep all season. I am still eating off those crappie from last year and the gills from ice season. Basically, don't be so quick to judge people.
Norm