1994 Honda Accord oil in spark plug well

As I was coming to a stop sign, my car started sputtering and almost died. I was able to get back home but as soon as I came to a complete stop it died. I tried to start the car and it would turn over but not start. I pulled the caps off the spark plugs and one was filled with oil, so I figured it was the valve cover gasket. I had the car towed to the mechanic and after him checking it out he tells my I need a new ignition switch. What does an ignition switch have to do with my car sputtering and dieing?