Whining is never an attractive form of behavior. It does appear, however, that whiners get rewarded in many organizations.
Supervisors and managers capitulate, in large part, to shut the person up. They may make a mental note to exact some indirect punishment at a future date, but it is unlikely even that feeble retaliation will ever occur. Memories fade along with the irritation. In the meantime, the whiner enjoys a special benefit.
The other employees, of course, take note of any appeasement. They know when the boss has caved, however cleverly the surrender has been disguised.
The whiner's jubilation is a body blow to the morale of their quiet co-workers and to the moral authority of the leader. What had seemed like a convenient accommodation, a small act, can have much larger repercussions. Moreover, the whiner is usually a repeat-offender with a series of victories that are really management defeats.
The damage may be incremental, but it is damage nonetheless.