Curious myself, I used the HackerNews search feature to find the first few theranos articles with significant points/comments.
First article, Sep 2013, top-rated comments include "The website design hides the message in frills and imagery, but the essence appears to be: Faster/cheaper blood-testing, via a smaller/quicker samples", "Yep, I still have no idea who they are or what they do.", "There are more soldiers in that board there than doctors. The only way I'd give them my blood would be to infect them with a disease." https://news.ycombinator.com/item?id=6349349
June 2014, top-rated comments include ".. zombie ... apocalypse". "What an odd cast for a startup board. I wonder what connects all these people, other than all being high-profile," and "The whole article was pretty weird. Anyone care to speculate what's going on here?" https://news.ycombinator.com/item?id=7951019
Oct 2015, top-rated comments include "Everything I've heard about this company is just weird", "investors throwing good money after bad, both to save face and to chase the glimmer of hope that they were getting somewhere with this," "Very smart. And very deceitful," and "Suddenly a company that looks like a Kickstarter page has the valuation of companies like Quest Diagnositics." https://news.ycombinator.com/item?id=10397149
I'd say HN was indeed appropriately skeptical (for the right reasons) by 2014 if not 2013, and certainly by 2015 (wikipedia says the first article seriously questioning Theranos was WSJ in 2015), HN was fully in board with the questioning of Theranos, commenters were not defending them from accusations.
But then, I don't know if that shows HN collective insight, so much as the tenor of HN comments tends to be skeptical/critical/negative. But they definitely were on theranos.