Product-Based Vs Service-Oriented

People who work in specialized domains or product based companies are so restricted to their own domain and products that they will know very less of anything outside. People who work in service based companies mainly work in any one project for a specified period of time and once the project is over, get on with another project which is on a totally different technology and domain. This is somewhat interesting and gives ‘looking-forward-to-the-change’ attitude as against the folks who continue to work on the same technology and domain for their entire lives. But then, since product based employees are working on the same technology and domain for years, it makes them experts in one field rather than employees of service based companies who belong to the category of “Jack of all trades, master of none.”