Here's my anecdote. I had painful but not debilitating RSI-like symptoms for a couple of years. For me, fixing this came down to a set of fairly simple things: the Kinesis Advantage keyboard mentioned in the article, setting a timer to force myself to take rest breaks, focusing on posture when working. At least in my case, the issue seems entirely mechanical, and I'm sceptical of psychological and emotional explanations like Sarno's.