I have heard people give a view supporting each position. Internal coaches, for example, can feel themselves unable to decline assignments that they think are unsuitable because they don't think coaching is the right intervention or they are not sure of their skillset in relation to the particular coachee. External coaches can believe themselves 'guilty' through ignorance as they try to work with conflicting messages about the contracted purpose of the coaching.
What have you experienced in either setting? Maybe we have members who have been in both situations?