Pavers are porous, and any spillage seeps into them and causes discoloration. Also, the pavers develop patches of rust, which make the pavers look dirty, old, and dull. Dull pavers are not welcoming, and most people would consider cleaning or completely replacing the pavers. However, cleaning the pavers does not guarantee a sparkling and appealing finish.
On the other hand, completely replacing the pavers is very expensive.
Others may consider sealing the dull pavers to prevent further staining and deterioration of the pavers, but considering the pavers are already stained, sealing would not hide the stains. Paver dying restores the dull pavers to being attractive. Over time pavers fade and become stained. Dying allows the various colored pavers to show color and the clear ones attain a new color that helps them to blend well.