Why reply to a brand new email instead of just responding to the original email address?

I’m a team lead, and my email signature has my contact info including my email address. I often jump in to the individual (shared and generic I.e “maintenance team”) inboxes of my team to try and help out as capacity requires. I’m so friggen sick of sending out an email on their behalf, from their email address and having people redirect the response to my personal email. Why would you do this? I want the team to take these comms back once their capacity allows, and my persona email is where I manage my own work, not theirs! Am I being sensitive, or this really dumb and annoying of people?