I'm not sure anyone said that. I'm pretty sure everyone suggested that dogs learn what's desirable by exposure.
Starlings are common throughout the province. I run into them while pheasant hunting. Pigeons are associated with buildings and structures. It's not six of one and a half dozen of the other. And in more general terms, we want the dog to lose its early interest in songbirds. Surely shooting a songbird for the dog is not the best way to achieve that end: experience and exposure will be teaching the dog to pay attention to small passerine birds.
I'll quote David Lisett: "Everything you do with a dog is creating a habit. So you can either create a good habit or a bad habit. Think about what you're doing."