Bobby Zirkin hosts “Across the Aisle,” a new Baltimore Sun podcast appearing on Tuesdays.Houston, we have a problem. Primary elections have unfortunately become low-turnout affairs dominated by partisan activists. But this year brought into sharp focus something that should concern us all. They revealed a growing reality that the election system is broken and that the ideological center is shrinking due to this flawed structure. We ignore the warning signs at our own peril. The lesson of this primary season is that extremism is on the march in this country. The most alarming developments occurred in New York City. Once...