I have a similar ratio, but I would welcome a time limit. Web I go its usually just to hang out for a bit, read a book, and maybe comment about the passing customers on Twitter. But if it is one of those one or two in ten times I plan to stay and there are people at every comfy chair with laptop plugged in, I'll leave without buying anything. So I guess we have opposite philosophies there. I don't think it would at all affect my patronage when I want a coffee to go.

This sounds like the case. Google is getting aggressive with its Panda updates, and as a previous commenter noted, the HN homepage is just links. Since that triggers Panda, it's a good bet that Google went a little overboard (not unprecedented).

> the HN homepage is just links. Since that triggers Panda

To be more specific, Panda is triggered by low quality/duplicate content. 'Penguin' is triggered by spammy/bad backlinks.

I'm not saying you're wrong (a page of links would look pretty low quality to google's algo), I just wanted to add on for clarity's sake.

Yes, I see where I was unclear. It's not the links themselves, but the lack of original, robust content.

The Panda update definitely pushed lazy/low-quality pages down the SERPs, but doesn't tend to deindex pages.

Also: while the page doesn't have any of its own unique content, it presumably still has high engagement and low bounce rate.

That's a good point. Hadn't thought the issue through that far.