One has to sift thru enormous amounts of information in order to find out what is true and what's not regardless of the information source. Doing so online is much faster than doing it in a hardcopy library.

Though, libraries may still exist, when the infrastructure to uphold the internet is long gone.
Anyway, that is not the point I wanted to make. What I wanted to say is that the teachers and lecturers in schools and universities have done the sifting already and so present to you what they have found to be important. And no matter how wrong they might be, on what is important, the fundamentals they have to teach you. That way you can get a faster overview of many scientific fields than by carving out the basics of them all by yourself, and I see it as highly important to have a basic understanding of many fields, to get a grip of the big picture.

It is a problem that many people are dwelling solely in their special field of expertise and that they cannot see beyond their own nose. That's why economists see every aspect from an economic point of view. It's what they know, what they have learned.
But to understand what's going on on this planet, to get the full picture and to make wise decisions for the future, you have to have knowledge of many different realms.
We have divided science in many areas, but in real life this division often doesn't exist and so a problem can touch aspects of many scientific fields. So if you watch a problem from your specialized point of view it is likely that you are missing something crucial, which could have dire consequences.

So, school is a way, to get in touch with those many fields, in a fairly compact span of time. For more in-depth knowledge you might fare better to do your own research, but for some basics, school is good enough. At least, where I live.

What I'd like to see in school though is the teaching of critical thinking from first grade on. That way pupils would learn to scrutinize what they were taught and it would get more difficult to distort the truth. So far the establishing of a critical mind is not only neglected, it is even discouraged. And that is, maybe, the point, where the school system really fails. It creates zombies that are willingly believing everything that a so-called authority, be it a scientific, political or clerical, spews around.