I've literally never seen a link to an HN comment go viral on social media, such that my non-HN friends would read it. It happens for blog/medium/substack posts all the time.
I've never thought about this, but now that you've pointed it out, I'm realizing this is genuinely a fantastic feature.
Sounds like yet another of the many perks of the spartan design here. All substance, with just a hint of (cascading) style.