Hot dip galvanizing protects in three ways:
It weathers at a slow rate, giving a long, predictable life.
The coating sacrifices itself to small areas exposed
through drilling, cutting or accidental damage.
If large areas get damaged, it prevents the sideways creep
Hot dip galvanizing is unique because the coating bonds metallurgically with the steel, giving a much greater resistance to damage than other coatings. And yes, with proper professional preparation, it can be top coated with paint.