Cardboard as a mulch

I can only see the permeability of cardboard being a problem if you're putting layer after layer of it down, or if you live in a very dry climate where the cardboard will take ages to break down. Here we get so much rain the cardboard gets soaked through and doesn't stay gas impermeable for very long. Worms and other soil life make holes in it, especially if its covered with something else like compost, manure etc. which sits on top and keeps the moisture in. A single layer is completely gone within a year.

I chortle at the idea that it's easy for everyone to put 4 inches of wood chip mulch down.