There's a belief that stop signs will slow traffic. Instead, they'll often result in people flooring it between stops, making up for lost time or whatever.
Other traffic calming measures do more to slow drivers down and improve safety while potentially making the entire drive faster, or at least more pleasant and efficient due to a steady speed.
I think we're starting to recognize that, but it's a lot easier to toss up another sign than to move a curb, and stop signs are seen as less of an "anti-car" measure.
Stopping and start every block also burns more fuel, increases pollution (cars emit most when accelerating), increases brake and tire wear, and makes drivers more frustrated and aggressive.
Other traffic calming measures do more to slow drivers down and improve safety while potentially making the entire drive faster, or at least more pleasant and efficient due to a steady speed.
I think we're starting to recognize that, but it's a lot easier to toss up another sign than to move a curb, and stop signs are seen as less of an "anti-car" measure.