It's maybe more like you don't hear noise in the system, until it's gone. And it's maybe not so much about actual "noise" but more of disturbances coming in through our networks affecting the performance of the streamer, even when playing files stored locally on a streamer it is being affected with a connected network cable. Similar to what the introduction of better DAC's did many years ago, people talked about a veil being lifted off their speakers. A switch was definitely a product I didn't think I needed in my setup a few years back, but hearing is believing.
I've been through the etherRegen and the Innuos PhoenixNET myself, the switch and network cables are to me an essential part of digital playback. The more frustrating part is maybe recently realising that while the switch is more or less a requirement it still can't do everything and the addition of a passive filter as in Network Acoustics Muon Pro solution after the switch will make things even better. In the Taiko Audio camp they're taking things even further and also want to replace your router creating a dedicated network inside your home.
As with everything in our hobby there's no right or wrong, you don't have to buy into anything and everybody choose themselves which direction to go with different solutions, but the better our setups becomes the more important all the details gets and everything all of a sudden matters, my advice is only for people to keep an open mind about the development in the digital playback domain as my feeling is that we're still learning a lot here.
As for money, I still think etherRegen is a good starting point for much less, to me the guys at UpTone Audio started this evolution and made us realise these things can be improved upon, but as with everything there will always be new, better (or only different) and more expensive solutions following any break through products. The next generation of etherRegen is also in development afaik.
Personally I can't wait to hear what the Tempus will bring to my already wonderful sounding system...