Vantaggi
For most tenured employees, fortunate for them to have ranked up from an entry level to a supervisory/managerial position. Just an investment of patience and loyalty to the company as well as consistent good performance and expertise on the role regardless of educational background.
Svantaggi
Tenurity as a way to move forward on a high position does not works for all, or a good and excellent performance does not mean you're qualified for a higher position. Some may have become stagnant or maybe too low salary increment as years passed by. There could have been a management biased. In a more positive outlook, sometimes the company is a good one for you or better to move on to the next one. It still depends on what opportunity is meant for you. Very low salary offer for entry level or fresh graduate even for an engineer with a relevant responsibility or at high stake role.