Most of the forces induced by a point particle follows the $1/r^2$ rule. Then why does the strong force not obey it?
Most of the forces induced by a point particle follows the 1/r^2 rule
No, it's the forces mediated by point particles with no mass and charge that follow the the 1/r^2 rule.
then why does strong force don't obey it?
The inverse square law is a consequence of the particles having no mass and/or charge. Such particles have long/infinite lifetimes and can travel to long distances so that they have time and space to "spread out" and cause their force to fall off with distance.
The weak force's W's and Z's have mass. Thus they have very short lifetimes, so they don't travel very far. As a consequence, they act over very short distances and then basically disappear. The weak force looks inverse square at very short distances, but disappears at longer ones.
The strong force's gluons are massless, so at first glance they could follow the inverse square. However, they also have color charge (as well as electric), which has entirely different physics. This gives rise to the creation of new particle pairs (mesons) that carry this residual strong force that holds nuclei together. These mesons are massive, so we're back to the first case again.
So two of the basic forces are inverse square. Two are not. And that's because of the particles that mediate them.