> I cannot find a single logical reason for why we would actually need character line limits when writing code

I always have multiple files open in my editor, side by side, since reading and understanding the code base is as much a part of the job as adding to it. With unlimited line length, this would be difficult. I would feel a little bit blind if I could have only a single code view open, as in the author's screen shot. Simple as that!

We don't have a strict policy about it where I work, but in practice, almost everything fits within an 80-column view.

"Show HN" is for something you have built that we can try out. Not for blog posts.