I'm currently the owner of several smartsheets as I maintain the Automations/help troubleshoot issues etc..
However, if the business unit has automations that go out to teammates, if they hit reply instead of opening the Update request , it comes back to me as the sheet owner and I wouldn't be able to assist if it is specific to the business unit (which it would be).
It would be nice to be able to set the Reply address per sheet so you can have a shared mailbox that would receive the replies and the business could take it from there.