This is just a mismatch with how HN posts pages and how projects expect their release pages to be read. Release pages are for users to know what changed. But HN likes to link to original sources and not articles about the source. In cases like this, we end up pretending the release page is meant to be read by a wider audience than the writers ever intended it for - not Apache's fault! Apache Arrow's homepage does have that one-sentence description on it ('A cross-language development platform for in-memory analytics').
In fact, if my coworkers (educators) are any indication, few people do.
Even 2 sentences on this page would've helped a lot.