First
is the availability of better conditions for the independence and impartiality of opinion compared to the internal employee, who may be affected by personal considerations and interests, and may be taken by enthusiasm for a topic that he does not see its negatives, and it may also be affected by the balance of power and influence within the company, so his advice is not neutral
Second
is the availability of better conditions to achieve the overall vision of the image, and the availability of this overall vision is a preliminary condition (among other conditions, of course) for the integrity of the advice, compared to the internal employee who may find it difficult to achieve this vision because of his intense involvement in his management or his intense preoccupation with the data of his job.