I use Steam streaming on a daily basis and it works flawlessly, both over 5 GHz Wi-Fi and wired. My gaming rig is essentially headless now.Yes, and it was laggy and horrible even over LAN (I binned it in the end).
But it tells you a lot about finicky network requirements. I have the technical expertise to make that happen, most gamers don't. There are scenarios, where just latency increases, when something goes wrong, and only a few knowledgeable people are able to remedy this.