Why do mosses and ferns need water for sexual reproduction, but not for flowering plants?

Unlike flowering plants, ferns, mosses and some other plants are always distributed only in regions where there is high humidity. This is due to the peculiarities of their reproduction. Such species are not spread by pollination, but by spores. Spores are completely defenseless in the external environment and lack the reserves of nutrients that flowering plant seeds have. They are forced to receive all the necessary elements with the help of water. If there is not enough liquid near the spores, the fusion of male and female gametes does not occur, respectively, the plant does not multiply.