Final answer:
Using internal sources to fill positions mainly disadvantages the firm by potentially demotivating employees who aren't promoted, which can lead to turnover. It may also inhibit the influx of new ideas and maintain existing disparities, affecting the organization's competitiveness.
Step-by-step explanation:
One primary disadvantage of using internal sources of candidates to fill vacant positions is the potential for creating discontent among employees who aren't promoted. This can lead to a demotivated workforce and may eventually result in turnover. Moreover, exclusively promoting internally may lead to a lack of new ideas and perspectives that external candidates could bring into the organization, potentially inhibiting innovation and competitiveness.
In terms of inclusivity and diversity, relying solely on internal promotion risks perpetuating existing disparities within the organization. It becomes crucial to ensure that internal promotion processes are fair and provide equal opportunities for all employees, thereby allowing everyone to compete on their own merits. This ensures that the workforce quality remains high, which in turn, positively affects the institution's ability to compete and succeed.