There's actually a website called carbohydratescankill.com?!?!? Well they can, if you include too much fat in your diet! All the successful civilizations had a starch/carb-based diet and really only started having major health problems after they started to include more animal products (high protein & fat) in their diets.
About Steve Jobs, Dr. McDougall looked into it and found, based on the evidence, that the most likely scenario was Jobs developed the slow version of pancreatic cancer when working with all those toxic metals at the HP computer company when he was still in high school and, if anything, his later vegan "high-carb" diet extended his life. http://www.drmcdougall.com/misc/2011nl/nov/jobs.htm
The low-carb diet is what got me sick and winding up here in the first place. Most of my symptoms are gone with no new symptoms since switching to a high-carb/mostly plant-based diet.