Papers published in scientific journals are often discussed on HN.

The original rationale for whether something belongs on HN was "anything that provokes the submitter's intellectual curiosity." That skews towards tech, but all sorts of other things fit inside that "big tent" of ideas.

Not everyone on HN is American. The Eurovision is interesting to a lot of the Anglosphere elsewhere, like the UK, Ireland and Australia.

And to indicate the size of popularity, Eurovision gets ratings of 182 Million viewers [1], which is roughly equal with the 172 Million who watch the Superbowl [2]

[1] https://eurovision.tv/story/Eurovision-2017-reaches-more-tha...

[2] https://en.wikipedia.org/wiki/Super_Bowl_television_ratings