121. When to and when not to use "the" - definite article

It was rude to people around them. It was rude to the people around them. Both are acceptable. It doesn't change the meaning since we know we are talking about "people around them" and not any other people.
Ex. Teachers in that schools are very good. The teachers in that school are very good. Again both are acceptable since we know which group of teachers we are referring to.
Children today are not very disciplined. The children today are not very disciplined. Both are fine since we know which group of children (today) we are talking about.

Now, in this example... "The article was written about the importance of teachers." ...adding a "the" would make it unusual without any context. However changing it to something more specific makes it work: "The article was written about the importance of the teachers specifically the ones teaching fourth grade matho the welfare of the tribe."

I think in general the trend in most languages is to drop words and to simplify. This may very well be the case here. While there is a discernible rule on when and when not to use "the" in this context, for practical purposes, it makes very little difference one way or the other.

Caveat: This is my opinion; I was not able to find references that support this.