As a diver, in backmount, sidemount or rebreather configuration, your rig and equipment should be clean, simple, streamlined and reliable. It is clear that redundancy is necessary for a higher level of self sufficiency and that if team members dive with the same or similar configuration this significantly improves diver safety.
Nonetheless we don't take what we don't need. Too much unnecessary gear creates drag, entanglement risk and will eventually lead to accidents. So, choosing and configuring your rig and equipment for safe and enjoyable technical diving is your first and very important step.