[Zobat]

Isn't this because upvotes "early" are worth more than upvotes later?

[clacker-o-matic]

Thats my guess; also survivorship bias. Those that make it have to show quick promise early on in order to hit the front page

[bilbo0s]

It's probably all of it.

I mean professional influence campaigns exist. Especially on social media. And HN also has its own required dynamics with respect to reaching the front page.