Desecration itemization

Why do we need different items to desecrate our gear?

Why isnt it enough that 1 item line with different tiers is enough?

Its just extremely confusing to me.

Item 1 desecrates ANY ITEM Between iLvl X and Y

Item 2 desecrates ANY ITEM Between iLvl X and Y

Item 3 desecrates ANY ITEM Between iLvl X and Y

Some system like this to simplify convoluted items being in the game for what reason? I really dont get it why you did not implement this in this way.