The pro is that carpet plants grow better in nutrient rich soil than inert substrate. The con is that working with soil based substrate is dirty, generating dust cloud whenever the substrate is disturbed. It’s fine if you have slow growth plants that rarely need manipulation, not so if you have fast growing stems that need frequent replanting.
Note that all plants can survive without rich soil as they can uptake nutrients entirely from the water column, though it may give a head start of some plants. Over time the nutrients in the soil will be depleted, and rejuvenation is needed from new soil or root tabs.