The idea behind using Reddit for product recommendation is the observation that an active community of enthusiast of some niche is hard to game by marketers - such community will try to moderate away spam, as it interferes with their regular discussion, and expert community members will be able to call astroturfers on their bullshit. It's orders of magnitude more reliable a source than in-store reviews and most review sites, as they're all thoroughly gamed and/or owned by marketers. But you do need a little bit of critical thinking to evaluate what you read there.
Marketing companies figured this out a long time ago. Even HN had a headline recently that was something like "use subreddits to drive app adoption".
Maybe "hive mind" is what you were thinking of (at least, I see it a lot in reference to Reddit)?
I would be careful about this on reddit. Subreddit communities are heavily influenced by fotm, everyone repeating the same thing(there's a word for this and i cant think of it...) Dissenting opinions to what ever is main stream gets downvoted. Reddit communities are also heavy on beginners. Those beginners often don't realize how much depth of knowledge they are missing.
It might be a place to bounce ideas off, but I would only go there after doing some of my own research. It should only be one tool of many.
In areas I consider myself knowledgeable, I see terrible advice given out. Often parroted by beginners. Like people in the headphone subreddit can give recommendations without listening to them. cscareerquestions is the blind leading the blind more often then not. There's no way to differentiate experience with someone fishing for upvotes or think they're being helpful by repeating someone else's advice.
I also think there's some astroturfing going on sometimes