Exactly why does mold or fungi grow better on wet surfaces?

I know that it grows better in wet or moist bread slices, but why EXACTLY? Because it speeds up the spore growth or something or because they can only grow on wet surfaces, but why??Exactly why does mold or fungi grow better on wet surfaces?
Remember that spores are created to facilitate dispersion and resistance to adverse environmental conditions. Moisture is a signal that favourable conditions for growth have returned, and encourages spore germination and subsequent outgrowth. Water is of course essential for establishment of the cellular environment and for metabolism to occur.