@atlvalet - you are correct in that the data itself is packets of 1’s and 0’s. None of the tweaks we talk about alter the data itself in any way and Ethernet and TCP are reliable at getting the packets to their destination.
I am a lifelong IT guy working in networking, security and infrastructure. I’ve been involved in building solutions that a lot of people use in their daily lives. I’m not an ultimate expert but I do know a fair bit after a lot of years of learning and doing.
1’s and 0’s aren’t everything, there is jitter, there is EMI and there is RFI. Domestic power is noisy due to the dozens of things we have plugged in such as our boilers, our fridges and freezers, our Alexa’s, and our neighbours too! Our houses are noisy from Wi-Fi and Mobile Phones too.
All of these things can affect the devices that receive the data packets adding noise to what we hear. I was sceptical too as I’ve read a lot of conflicting opinions. The main thing I noted is that the people that say these tweaks can’t work "because of physics" etc. haven’t actually tried them in their own homes, with their own kit and most importantly their own ears.
Are there preconceptions and biases when we listen to upgrades? Of course, there are! When I change something I expect a difference, however, I don’t assume it will be a difference that I like in my setup.
So as a lifelong techie and a bit of a sceptic, everything I have purchased has come with a money-back guarantee so if I don’t like the difference i.e. I don’t find it positive to my enjoyment of music back it goes (and I have done this).
To your main question, why don’t the expensive boxes we buy as DACs and Streamers etc. do this for us? Yes! Quite so! Well some do have a good crack at it, and the more you spend the better the clock, or the better the PSU, and in some cases, the better network interface with some noise reduction tech.
But, there are some very well-respected audio experts out there with no commercial incentive to like these extra magic boxes and doo daa’s and they have very high-end systems, often with dedicated power etc. and they still hear improvements in their music that they like with these widgets. Therefore investing in them now doesn’t make them redundant when I can afford to spend more in the future on better components (though my budget gear is starting to sound marvellous).
And on that note, I’ve ordered a better USB cable and a SotM ISO-CAT7 Ethernet filter :D