This dude doesn't understand what a CAM table is, so I feel like this quote is just laughing at an idiot who thinks he is smart. Which I'm not necessarily against, but then you have tons of people in the comments who are "good with computers" who don't understand it either.
the tl;dr is that this guy doesn't have a clue and anyone who is "looking for a computer" without logging into the network infrastructure to find the MAC is just an idiot.
God forbid a person doesn't know something in a highly technical field. Not everyone is a CISCO certified network engineer, some people build home LAN networks for fun or self-host in order to learn new things. I highly doubt you never were stumped by a network behaving strangely, or had a brain fart moment and misconfigured something. Learn some humility.
I mean that's fine, but he is posting on IRC and bash. Casual people don't post there and have no idea what those things are. But this guy specifically thinks very highly of himself in a technical capacity, but doesn't understand basic networking. People like him make everyone else's life worse.
You know nothing about the OP, besides the fact that he posts on Bash. IRC is very familiar to an older generation of users, and people join technical communities to learn new things. How is asking for help making people's lives worse? RTFM is a common response, but first you need to know which M to FR in the first place, and a helpful nudge from someone in the know helps a lot.