A colleague may be a peer, but also a competitor for resources. A direct report may be trusted, but you still shape their career. Your manager may be supportive, but also evaluates you. A spouse or friend may care deeply, but have their own hopes about what you should do.
None of these relationships are flawed. They simply carry context, and context changes what can be said without consequence.
The cost is often subtle
The problem is not that senior people have nobody to talk to. They usually have many conversations. The problem is that each conversation has a role attached to it: persuade, decide, reassure, delegate, negotiate, update, defend.
Very few conversations exist only to make the thinking clearer.
Private uncertainty has value
Leaders are often rewarded for reducing uncertainty for everyone else. That can create pressure to resolve their own uncertainty too quickly. But private uncertainty is useful when it is still doing analytical work.
You may need twenty minutes in which you can say the half-formed version, contradict yourself, admit that you dislike every option, and change your mind without somebody treating each sentence as a commitment.
Neutrality is a practical feature
A neutral listener does not remove accountability. You still own the decision. What neutrality removes is the need to manage the listener’s stake while you are trying to understand your own.
For some decisions, that small reduction in social complexity creates disproportionate clarity.