I don't think you can expect manufacturers to anticipate every possible scenario for noisy power, noisy environment, vibrations, RFI, EFI, etc. The costs would be very high for those components. Should everyone pay for those features if they do not need them? They design to standards and our homes must conform to certain standards. The same for the modem and router. Beyond that, it is up to us- the hobbyist to either accept the performance as is or experiment and find ways to enhance the sound. That goes from what is most obvious and accepted such as isolating your turntable from mechanical vibrations to the more controversial audio grade Ethernet switch and silver plated Ethernet cables. Results vary from user to user which should be no surprise. A DAC or music server may already have adequate isolation or perhaps its performance is of such a low level that a difference cannot be detected.
I have an 8 meter run of balanced cables from my preamp to my amps. My shorter runs are also balanced connectors. Nowhere here was it mentioned that the output of DACs and preamps is higher for balanced out than for SE. I consider that another benefit. I also like the connectors much better than RCAs. Some electronics may have XLRs but not be a true balanced design. In that case figure no electrical advantage over SE.