Truth:

For decades, [making yourself indispensable] has been the Standard Operating Procedure for people in a variety of roles and industries, from the developer aiming to be the only one capable of maintaining his own code, to the Project Manager who insists that certain processes couldn’t run without his oversight. Half a century ago, this kind of behaviour might have guaranteed one’s lifelong employment. Today, it will harm their career. Worse still, the knock-on effect can undermine the company and even the industry.