Not just for touring bikes anymore...
If you watch the 1973 Giro d’Italia highlights on YouTube, you might spot José Fuente (who won the Mountains Classification that year) using barcons. Maybe I don’t get out enough, but I don’t remember ever seeing a world-class rider using them. They obviously didn’t hinder his performance. Or maybe they did and he might have beaten Eddy Merckx if he had used traditional down tube shifters. No... probably not.