Employee leaves company after 12 years, manager tells him the company would've created any job he wanted if he had asked for it: 'Why tell me now, as I'm leaving, that my dream job was supposedly in the works?'

Neither of them did a good job at communicating. 

There are a couple of different ways to do a job. You can do everything you're technically "supposed to do" perfectly, and be the best at your role and nothing more. You can branch out into different departments and try new things to strengthen your department and increase company-wide synergy. You can coast by for as long as possible, doing the bare minimum, until you eventually lose your job. Many managers believe that the best employees are those who do much more than is written in their job descriptions because they are the most committed to the company's growth and mission.

It can be difficult to parse how much you should stray from your job's original duties. If you get too far off track with extra projects and unrelated tasks, it can be to the detriment of the work that you're supposed to be doing. Some bosses see an employee trying to broaden their horizons within the workplace as them overstepping their bounds and sticking their nose into places it doesn't belong. Some managers don't want their employees to do more than they're asked to, because employees might then expect compensation for the extra work they did without being asked. It's essential to communicate expectations with your employer or employee so you can find a balance that works for both of you.