When I lived in Chicago I was only blocks from Wrigley Field, skies don't get much worse than that as only the very brightest of stars were visible naked eye and it was often a challenge to spot even them. While there, I used a 6" dob frequently and introduced a large number of people to astronomy in the process. The Moon and most of the planets are visible as well as a large number of asterisms and open star clusters. There are even a few DSOs that can be discerned; though their appearance is markedly less pronounced than from darker skies. I moved there from Bortle 3 skies, so the transition was quite noticeable, but still there's plenty to see; enough to keep one active for a lifetime.
The look on someone's face when they see the Moon, Jupiter, or Saturn through a scope for the first time is a beautiful thing.