But "Why does it need to exist?" kills every art project, side project, or anything built for the love of building. None of those need to exist either.

There's also the argument that if something isn't forbidden, it should be allowed. The way you lose rights over time is by your existing rights getting clipped off at the edges.

A lot of the criticisms leveled at me here would also apply vs Google back when Larry and Sergey were grad students. If they'd had to worry that indexing content equals copyright infringement, they'd have a steep hill to climb.

Regarding copyright, copying for display purposes non-commercially seems to be fair use. There are four factors to fair use analysis: purpose (non-commercial art project), nature of the work (short factual public comments), amount taken (individual comments in context), and market harm (none, your comment still exists on HN and YC loses nothing). Three of the four factors favor fair use, and arguably all four.

The point is, it's not as cut and dry as you're portraying it to be. If you post data publicly on the internet, you should expect it to be read. The current legal system seems to support this theory.

Since this neither violates the CFAA nor copyright, it seems ok. Publicly posted content carries an implied license for reasonable access and display. That's why you can quote HN comments in a blog post without getting sued.