Let me address what I can. You said:

"It's certainly good to learn the basics but I think this tutorial is a bit dated now."

then

"I don't disagree with you at all. As I said, it's a great tutorial for the fundamentals and the securtiy considerations are of course important still but I think it is also true that there are more recent approaches to writing web-apps and I would recommend exploring those."

Personally I think the tutorial in question is pitched at exactly the right level for someone new to CGI. I can't think of a better freely available online resource that is comparable, which isn't so say one doesn't exist. The fundamentals/security know how is important regardless of using plain old CGI or a framework. Should they want to move on to using one of the many frameworks available there are plenty of resources devoted to each specific one, and some providing comparisons between them. IMHO that's another learning curve, over and above (rather than instead of) learning what is taught in the tutorial I linked to.

Essentially I believe in using the right tool for the job. Depending on what exactly is going on a framework may be overkill, where a simple stand alone CGI script or something like this may be all that's required.

"I mentioned database interfaces because the OP described a scenario where a CSV file would basically be used as a database - including update operations. To my mind, this is going to be highly problematic in the long run and I'm not sure if your post agrees or disagrees with that position(?)"

My post made no comment regarding the database aspect, again depending on the exact requirements I'd probably move away from a csv based database. By the sounds of it DBD::SQLite would be more than suitable for this task.