They’re saying 50Mbps 4k is shitty, not that 4k is a bad example. Modern Wi-Fi can definitely handle high-bitrate video 99% of the time, but that 1% where someone turns on a microwave can cause hella buffering. If you have the ability to run ethernet there’s no benefit to using Wi-Fi.
Seriously, I was going to add my WiFi6e is theoretically way overkill for my limited usage and that’s supported by speed tests, yet I do notice its limitations while gaming. It’s got the bandwidth, it’s even got the low latency, but it also has the glitches. Until that speed is reliable enough to never impact my games, it’s not worth being my first choice
Even then, wired is better where appropriate because it just works. The more devices I can put on Ethernet, the fewer require the extra setup of wifi, the extra risks to eavesdropping and single points of failure, and yes the fewer where I ever have the frustration of glitches
