Part of the issue is our built-in bias towards thinking of other Reddit users (and HN and whoever) as people just like ourselves. That means we give undue weight to their recommendations.
I definitely find myself being more swayed by a single user's recommendation with maybe a few dozen upvotes, over SEO-gamed websites and Amazon reviews. But in reality, that's a ludicrous assumption, since advertisers knows it too, and it only takes 5-10 fake accounts to create that kind of pretend consensus.
In many ways, Reddit is far easier to spam.
It takes me much less effort to do the former than the latter.
Usually, a great product will have enough activity surrounding it that it's difficult to fake with bots. Especially, Instagram profiles with <1000 followers + non-seo-optimized stories/posts raving about something signals that the the <joy-from-product> is organic rather than manufactured.
I think the strongest signal for legitimate IG accounts is the ephemeral nature of the 24-hour IG stories. I suppose someone enterprising could auto-build hundreds of personas that post stories daily, but a random profile with stories posting activism, their morning latte art, a selfie with some friends seems doesn't fit in the ROI of a scalable marketing strategy across a ton of accounts. Maybe I could be wrong?