There are other things that can influence the balance. Chazal tell us that the middah with which you judge others determines the way you are judged. The amount of strictness or compassion you exude becomes the standard by which you are then measured. And extremes in attitude or behavior can bring extremes in the system of judgment.
Machlokes has the power to bring about extremes. When people cleave to hostile groups, their opinions and attitudes become severe. There is no tolerance, no understanding. You are on our side or theirs – you are a tzaddik or a rasha. Because the divide is sharp and acceptance non-existent, the middah of din flares, and when that happens, judgment is at its strictest.
This seems to be the answer to Rashi. Korach launched a rebellion, bringing about a complete divide in the nation. Because of this, complete din was brought into operation. Now there were no mitigating circumstances. No considerations. If something comes about through you, you are responsible. And so, the nursing infants were judged. Not for their intentions, not for their plan, but for the outcome. Through them the rebellion was larger. It was no longer two hundred fifty men against Hashem. It was now two hundred fifty men and their wives and children. Each person added to the group. Whether they recognized what they were doing or not, whether they realized it or not, the revolution was larger, and the price had to be paid.
This is a powerful lesson for us on two levels. First, in terms of understanding the extent of responsibility and the remarkable advantage of being judged with mercy. And second, in practical terms, while no one wants to be involved in a machlokes, it is all too easy to get pulled in. Often, without meaning or intending to, we find ourselves on one side or the other, and before we know it we are deep into the thick and thin of it. The Chofetz Chaim writes that machlokes is like a raging fire – anyone nearby gets burned. By recognizing the effect of such disputes and the mortal danger we place ourselves and our families in when we get drawn into machlokes, it wise for us to heed the advice of our sages and run from it like we would run from a fire.