So who is "they"? Since when can you read other people's minds?
I'm on this forum. I bought a Mazda. I read about problems.......and I'm not the least bit worried.
People with problems, whether it's car issues, health issues, financial issues, whatever, will seek out answers.
No-one I know calls their doctor, or goes to the hospital, just to let them know they're feeling great and that they're not sick.
I was in the service business all my life, and no-one ever called in to customer support to tell us their machine was working great.
Same with forums. I'm on more than one, and yes, like you say, they are all basically the same.
People come on there to get answers to their problems, and sometimes just to brag about their cars. Great.
Does that mean we should assume that everyone else gets worried and that the sky is falling when they read about a problem? I don't think so.
I like my new car very much, and if and when there's a problem (which eventually there will be), I'll deal with it without getting my knickers in a knot......and I might make a post about it....lol.