I kind of agree with this. As a computer/software engineer I have always felt that any network switch can only make very minimal differences, if any at all. If you get your music through streaming services realize that the signal that final gets to your DAC has already passed through hundreds if not thousands of routers and switches. One final "audiophile" switch at the end of the line should make almost no differences. Also, your point about that a properly designed DAC will already take care of any issues is on point.
I have tested both streaming, files stored on a network drives, or local stored files on internal drives within the sever. The internal stored files sound better in every case so long as we are comparing the same files. We even performed this test on my buddy's system where he recently had his entire house rewired with "audiophile" wiring; ethernet cabling and network devices. The internal stored files were superior.
This was even more the case when the files were stored on solid state drives (no moving parts, no spinning drives), and especially true when the files are stored on M.2 drives. The music comes straight from internal SSD drives to the DAC. Nothing in between. The music server/meta data/control software is on the sever computer/streaming device and sends the music straight to the DAC which in turn outputs the analog signal via high grade balances cables to the pre-amp. As straight and minimal path as can be achieved in a digital system.