> Wasn't this specifically some lame-ass attempt to combat some click fraud or something these extensions were doing?

No. That you believed that was just an unfortunate consequence of HN's kneejerk tendency to upvote middlebrow dismissals to the top comment, which resulted in people rushing to craft apologetics for what is in reality bonafide scumminess on LinkedIn's part, which itself resulted in confabulations like the claim that, "It was all extensions related to spamming and scraping LinkedIn last time this was posted"—which is simply untrue.