There's often not a lot to say. You read the paper, say "that's clever", and don't really have anything to add.

I consider those "aspirational" upvotes.

HNers like to think of this place as a community of smart people, so we upvote stuff we think smart people should enjoy, even if effectively haven't payed attention to the content.

I think it's not specific to Haskell but more specific to CS papers. More accessible (and a bit more ranty) material quickly gets a number of comments, e.g. https://news.ycombinator.com/item?id=10300213

The main reason may be simply that it takes time to read such a paper. It takes me at least half an hour to read the first 3 sections.

This is always a real pleasure to read a paper like this, which dives us into the matter at the first sentence, gives a good overview of the stakes as well the concerns, and sketches the solution skeleton with convincing arguments.

Nonetheless, this would require to be more deeply involved into the domain, to be able to make insightful comments or even to point to related papers or alternative approaches.

nobody understands haskell, they just like to think they do ;)