I suspect this is a very large part of it: the internet is a tool that amplifies.
That amplification includes those few who have the dangerous little bit of knowledge, which the circumstance the OP references, those who know a factoid and are desperate to share that wisdom without really understanding the rest of the story.
Meanwhile those who don’t even know that factoid, those who know more of the rest of the story, those who suspect there a test of the story, and those less desperate to post, say nothing.
Selection bias operates and the ones we hear are almost only of that first group. And a few with an intelligent question about squash growing or admiration for your gardening… but only a few