A lot of pilots don't use ILS and use a visual approach. That was one of the issues with the SF airport, as the left runway was closed, the lights were off and the pilot lined up with the taxi way.
While it is true that the normal lighting was off (because it wasn't a valid runway at the time), there was a lighted, flashing X to indicate that fact. Along with the fact that the taxiway was not illuminated as a runway, and the pilots were notified about the runway closure…
