There are few who would argue against the merits of getting an education. The further you go, the more benefits you often find along the way personally and/or economically. Historically, denying an education has been used to oppress certain individuals and uphold rigid class systems. No surprise, those who have or were often denied an education or given very little were slaves, peasants, lower castes/classes, those in more rural areas, girls/women, the poor, people of color/immigrants, and those in strict conservative religious systems.
Why would you deny a people the right to an education or cut them off from being able to further their own education? To answer this, you must look to those who benefit from this action. Take a strict conservative system like the Mennonites or Amish. They offer an education basically to about middle school, then there is no more formal schooling offered for most and the education that is offered, no surprise, is heavily based on bible teachings and less about things like history or geography or English lit because to teach those would invite further questioning---"where is France," for example, "what language do they speak, how do I get there?" The goal of these communities is to keep their flock within. If they start wondering about an outside world or start seeing pictures of people who look nothing like them, they may want to go see or explore for themselves.
You cannot exert total and unyielding control over people who understand the free will of an education. You see this in places like North Korea where the educational system, books, papers, tv, radio, and the internet have been heavily censored and manipulated to create a distorted view of the world, but those who have discovered it on their own in secret and educated themselves either through escape and/or self-education do as most of us do---which is understand not only the limitless potential of this knowledge, but what we can do with it.
So why should be care if someone "out there and over there" doesn't have an education? In 2021, we are a global society where it is becoming abundantly clear that no man or woman is an island. The world needs more minds and people working to help solve global issues and local ones that plague our societies. Keeping people relegated to the most basic or a poor education means we are potentially limiting the world from ideas that may help to better it or save it. Think about a space shuttle. How many collective people around the globe did it take for us to figure out how to get to the moon? How about to figure out a Covid vaccine? How about to prevent a war from happening? Each person has the ability to contribute knowledge to the future success of humanity but if we keep suppressing this knowledge, we are only ever hurting ourselves.