First, I totally get where you are coming from. Yes, the best thing would have been for this person to google "How do I chdksk /F a drive?" But since you're making stereotypical assumptions about their skill levels with computers, I'll make one about you and assume that your social skills aren't that great and help you out as to why this person probably FELT like you were telling them to JFGI even though you didn't.
It was most likely the condescending, "but if you are this new to windows, have your support do this for you. Watch what they do and ask how they do this. Take notes if need be."
Guess how I got to this forum? I was googling my issue and trying to figure out how to solve my own problem. I didn't know how to CHDKSK /F all drives either and while most of the time I would try and google it, in the moment if I was having a discussion with someone about it, I might slip and ask instead. It's your assumption that this person is an idiot or ssssoooo new to windows that they need to be talked to like a 5 year old. Just because someone doesn't know something you deem basic, doesn't mean they are a total noob. Sometimes computer experts seem to forget what is truly basic and what s not. I am by no means a computer EXPERT. I don't have a computer science degree. But I'm also not a total noob. I'd like to think I'm on the high end of the middle somewhere. I've been using computers pretty proficiently since DOS when I was a kid and I didn't know CHDKSK either simply because I have never had cause to use it or come across it.
It's very possible this person is all the things you assumed about them with your condescending tone. But it's also just as possible that they were just asking for some clarification since you guys were talking anyway instead of googling and would normally google.
Biggest take away, just because someone doesn't know what you know doesn't mean they never try and are and idiot.