I'm a sysadmin at a small shop and it amazes me how many of my coworkers don't know about or don't use netcat. Netcat, s_client, and nmap are super useful for quickly narrowing down the cause of a problem. I have been guilty of using nc to transfer files before, it's a good trick to know about in a pinch and where you aren't worried about the lack of encryption.
Sidenote, it could just be my Lemmy client but this post doesn't seem to actually contain a link to the article.