In the context of articles the answer is simple: because the journalist isnt the specialist, they likely just interviewed a few people and wrapped it up the article.

For comments it's a different story. You do occasionally get the real experts, but more often then not, you just get another mediocre human like myself that just voiced their opinion. Furthermore, there is a strong correlation with experts not commenting as they've got better things to do vs the average Joe that is commenting with little effort, essentially outputting significantly more comments. Another detrimental factor is that mentally unwell people will often output orders of magnitude more comments then everyone else, complicating everything even more.

OP has a point. It depends on your frame. Some areas require far more specialized knowledge than others. If your specialization were something incredibly complex like quantum physics, you'd probably find ridiculous mistakes in 99% of mainstream sources. OTOH, articles about business or tax law may have far fewer lay errors, so you would be mistaken to project the popular information error rate in your own field onto popular reporting in every other field.

At least in theory, while the journalist isn't a subject matter expert, they have spent time reporting on the same domain. They know the people who are experts, and work under an editor who has worked in that field for decades. They should be able to validate any facts and be able to put them into context.

As newspapers have gotten hammered there are fewer and fewer people who actually do that, and more and more bloggers with loud opinions and few facts. Many good sources have gone defunct or given up trying. But there do remain a few sources of decent journalism, where the reporters and editor really are better informed than most laymen.

> You do occasionally get the real experts, but more often then not, you just get another mediocre human like myself that just voiced their opinion

Most of the comments experts make are just stating their own opinions as well. Take any credible expert in any field and you'll find equally credible experts who completely disagree with them. When experts are communicating with non-experts they're often really bad at explaining which points are just their opinions versus more widely accepted facts, and just as bad as explaining what other equally credible expert perspectives exist on a topic other than their own. They also tend to be pretty bad at explaining where the limits of knowledge in their field are as well.

I would suggest that the ego boost of being a highly regarded expert also tends to make these shortcomings worse with a lot of people, that increasing credibility and reputation can have the effect of increasing dogmatic-ness. Of the topics that I'm somewhat well informed about, I know very few "experts" who are good at explaining the perspectives of their field in a reasonably balanced way, I think Roger Penrose is quite good at doing this, but even he's not perfect and experts with his level of humility are not very common.

Sure. I mean, ask most coders what the best programming language or web framework is for a certain job, and they'll tell you it's whichever one they use. It's partly confirmation bias from their workplace, and partly "when all you have is a hammer..."