[throwanem]

An ongoing major incident is already stressful enough for everyone involved, and looky-loos don't help that at all. Nobody does a better job of debugging for having to fight a helmet fire at the same time, and one of the IC role's responsibilities is to proactively minimize that risk as far as possible.

It does depend somewhat on the situation and the organization, and on the role; IC engineers observing for familiarization is fine, VPs joining never is. My approach is that the incident call is for those actively involved in the investigation or who have been invited to join by those who are, including engineering ICs who wish to observe for familiarization. Meanwhile, stakeholders not directly participating in response receive updates from the incident commander via a separate (usually Slack) channel. Managing that communication is also part of the IC role, whether directly or by delegation.