[imtringued]

You are creating a new spreadsheet that you can save as an xlsx. What you are looking at is not the CSV file itself.

[NoboruWataya]

This is a distinction that does not matter to most non-technical people.

[john_the_writer]

Well I mean unless you're inspecting it with a hex editor, you're not looking at the csv file itself. Even then, I suppose you could say that's not even the file itself. An electron microscope perhaps? But then you've got the whole Heisenberg issue, so there's that.

[eviks]

That's not true either, try it yourself with a simple csv file, open it, add a row and save - you'll see the original update

(there are some limitations)

[tokai]

You are missing the point so hard its hilarious.