Solutions flow easily and can thus form a stream in industrial processes. Solutions often intermix completely, thus ensuring intimate contact of their contents. In contrast, gases and solids are a pain to work with. Gases keep trying to escape from whatever contains them, sometimes explosively. Their reaction vessels must be pressurized and are more expensive than solution vessels.
Solids are often recalcitrant about mixing well.
All in all, solutions are a real blessing. It need not be a solid, as you might guess. The solute could be a gas which will dissolve in the fluid phase, like the CO 2 in soda. Or the solute could be another fluid that we're merely trying to dilute. The solvent is the fluid phase in which we intend to dissolve the solute.