First, I'd like to supplement with general info about SL 5x5 so I can put my question into context.
Sometimes in the newsletter emails I get from Mehdi where people ask him random questions about stuff like plateaus, he'll reply and say "you'll be amazed that you can add weight effortlessly after every workout. That is, if you didn't start too heavy to impress people in the gym".
Now, there are a few things he could be implying. He could either be implying that people start too heavy and have bad form, thus legitimately limiting their ability to properly lift a heavier load. He could also be implying that if you can comfortable squat with 150lb as a starting point that you shouldn't do it.
Does the whole starting with the empty bar actually enter into anything significantly if you actually CAN start some of the workouts with good form at a comfortably higher weight?