Why is M1*V1 = M2*V2 only used for diluting solutions?

Why is $M\_1V\_1 = M\_2V\_2$ only used for diluting solutions? Why can it not be used to figure out how many moles to add to make a solution more dilute?




As Satwik has stated in the comments, the equation relies on the conservation of moles principle. 



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> $$\dfrac{mol\_1}{V\_1} \times {V\_1} = \dfrac{mol\_2}{V\_2} \times {V\_2}$$
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Based on the above, given a constant volume of a solution, adding more moles of solute will only make the concentration increase, not decrease. Adding in more solvent is the only answer in that case.


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