I believe it’s because currents of air rotate in the opposite direction. So to cross the equator the air would have to pass a boundary of global air currents which are going counter to the hurricane’s motion. See this picture for a reference.

Coriolis effect. Things spin opposite direction across the equator due to how the earth spins.

It’s virtually impossible for a hurricane to cross the equator.

Because of things like Coriolis effect and convective currents, there just aren't winds that blow across the equator, not at the scale that would blow a hurricane from one hemisphere to the other anyway.

Winds tend to blow along and away from the equator, not across it.

For ELI5, think of it this way. The earth is spinning, and at the equator it's moving really fast, like 900 mph. At the north pole, the earth isn't moving at all, so in the northern hemisphere, you can picture all land to the north of you as moving slower than you, and land to the south as moving faster than you. If you run south, it would spin you because it's moving 'sideways' faster than you are. Cross the equator and suddenly it gets slower as you run south, literally putting the brakes on your spin.

The ancient city of R'yleh is rumored to be somewhere along the equatorial line. In ancient times was known as the torrid zone, an infernal place which claimed all the lives of those that cross it. Hurricanes are a force of nature and, since no two forces of nature can overlap (like a volcano during a storm or an earthquake and a flood) the hurricane can't go where ancient ones dwell.