When you’re sucking the air away it still generates a current over the dishes, but also carries the saturated moist air away so that new drier air replaces it, which becomes saturated and carries more moisture away. When you’re blowing the moving air impacts upon the dishes and breaks the flow so the moisture stays closer to the dishes.

Just guessing though.

because blowing sucks.

Drying happens when the moisture on your dishes gets evaporated into the air. If the air is already moist. It happens slowly. The air in the just opened dishwasher is hot and very moist. Blowing away removes the vapour/ moist air from the washer compartment, which gets replaced by the drier air in the kitchen. Blowing towards just keeps the moisture circulating inside, and though some of it will no doubt eddy out, it isn’t as efficient, it seems.

While blowing, some of the fan’s energy is spent on increasing the pressure inside your dishwasher, which increases the density of the air the fan blades move through, increasing drag on the fan blades causing them to move slower and create less airflow.

While blowing, you’re also pushing moist air to the back of the dishwasher, and after that air reaches 100% relative humidity, it can’t hold any more water and will not help dry your plates. Some of it will eventually escape around the sides, but some of the airflow your fan creates just circulates humid air around the inside of the dishwasher.

Turning your fan around solved both problems. It increased the volume of air flow, and decreased the relative humidity of the air flow.

Maybe it is something similar or related to: https://youtu.be/XP6oqIic4lo (apologies for youtube link)

I would guess that it’s moving moisture away from the vicinity. Blowing it far away instead of inwards to the kitchen. Then normal evaporation can happen better.

But I think you really don’t need to bother, why not just let them dry?