Earlier quoted context omitted.
There are already numerous third party sites that crawl HN and use its API. Your comments here are public, no one needs your permission to use them.
So if you put a photo up on instagram I can yoink it and use it as I see fit? I suggest reading the legal print: https://www.ycombinator.com/legal/ > By uploading any User Content you hereby grant and will grant Y Combinator and its affiliated companies a nonexclusive, worldwide, royalty free, fully paid up, transferable, sublicensable, perpetual, irrevocable license to copy, display, upload, perform, distribute, sto…
We're talking about Hacker News, not Instagram.
>It says here I grant Y combinator (and its affiliated companies; hm...) a licence, not that I grant it to some rando with a scrapper (or using an API).
And yet Hacker News has an API and plenty of people use it, implying that Hacker News considers the use of its own API to be valid within the context of its "license" and by extension any application also using the API.
Feel free to lawyer up and sue, though, and let us know how it goes. I don't think it'll go as well as you seem to believe.