Read those threads more carefully. The first only claims there are ways to boost OR identify YC alum posts (pg clarifies). The second implies you get a "boost" but does not say that HN itself gives that boost.
As someone who tangentially interacted with YC founders, I can confirm that HN does not inherently boost posts, but HN does identify YC alum posts to other YC alums, which is probably the source of the "boost". In fact, HN on several occasions has penalized YC alum posts (upvote ring detection).
As someone who tangentially interacted with YC founders, I can confirm that HN does not inherently boost posts, but HN does identify YC alum posts to other YC alums, which is probably the source of the "boost". In fact, HN on several occasions has penalized YC alum posts (upvote ring detection).