Chiang and Netziv

(1) Everyone on earth had the same language and the same words. (2) And as they migrated from the east, they came upon a valley in the land of Shinar and settled there. (3) They said to one another, “Come, let us make bricks and burn them hard.”—Brick served them as stone, and bitumen served them as mortar.— (4) And they said, “Come, let us build us a city, and a tower with its top in the sky, to make a name for ourselves; else we shall be scattered all over the world.” (5) The LORD came down to look at the city and tower that man had built, (6) and the LORD said, “If, as one people with one language for all, this is how they have begun to act, then nothing that they may propose to do will be out of their reach. (7) Let us, then, go down and confound their speech there, so that they shall not understand one another’s speech.” (8) Thus the LORD scattered them from there over the face of the whole earth; and they stopped building the city. (9) That is why it was called Babel, because there the LORD confounded the speech of the whole earth; and from there the LORD scattered them over the face of the whole earth.

Lest we be scattered over all the face of the earth - However, we must understand why they feared that someone might leave to another land. And it is understood that this was related to the uniformity that was among them. And since the opinions of people are not identical, they feared that people might abandon this philosophy and adopt another. Therefore they sought to ensure that no one would leave their society. And one who veered from this uniformity among them was judged with burning, just as they did to our forefather Abraham. And the "same words" can also be seen as the fact that they would kill whoever did not think like them. And more is explained on verse 6.