According to the article Armenia makes chess compulsory in schools, Armenia made chess mandatory in school for the sake of discipline. A lot of people in the real world don't work together to organize plans properly and really suffer the consequences later so I suspect Armenia figured that kids need to get disciplined in order to grow up as a person who works harder to organize plans. Maybe the Carnegie foundation did some research on it.
As an extra note, I found out about the Carnegie foundation from the question What does math education research know about difficulty vs. effectiveness? Maybe some day, there will be some Stack Exchange users who will be very willing and able to adopt an advanced research technique with one another. Then through that technique, they might eventually eventually find a connection between this question and the question What does math education research know about difficulty vs. effectiveness? through my reference to it in this question and then help direct Stack Exchange users to many very similar questions.