There definitely are concerns which shouldn't / don't need to be shared widely, when they're about specific people or about interpersonal issues. There's also potentially lots of stuff that should be communicated to the team, but they don't need to know the details of the issues. You definitely don't want to start a "John is avoiding work recently" conversation in a group, exactly because everyone can hear it and respond to it. Maybe the manager needs to have a private chat with him, or maybe the manager already knows that John had a death in the family that affects him. Not everything needs to have more people involved.

Which is an extremely naive view. Some concerns are sensitive.

If you listened to his response it was very much centered on his communication whether he intended it that way or not.

I guess I should have elaborated more about the ICs. With experienced employees they should know how to provide feedback to a larger group, but you don't necessarily have that with junior or intermediate ICs who don't always have the confidence to say anything if you didn't provide them with a space to provide feedback or just have a complaining session.

It can also be just the possibility that feedback could be taken as personally attacking someone in a group setting. How does someone differentiate between general feedback and passive aggressive feedback singling them out? For someone that may not "fit in" with the group they are part of it is a real concern they have to consider. I can think of many examples where this is the case where the suitable action is to either give or receive feedback in a more private environment.