Not really needed, but it can be a convenience feature. I have the Roon streamer, TV, Roku, etc. all 50’ away from my router, so the switch lets me run 1 cable (in-wall in this case) and hook up all my devices.
You'll never be able to convince me that an audiophile switch is worth it, but I do use an Ethernet isolator to reduce the chances of surges and induced noise.