With plants such as anubias, java ferns, java moss, anacharis and hornwort, substrate is fairly unimportant, because these plants are usually attached to rocks and driftwood or even floated (rather than burying the roots in the substrate). They get their nutrients from the water, not the substrate.
I've got cryptocorynes in my tank (roots buried in shallow gravel) who still do fine because I fertilize with liquids in the water column. I notice the roots of these plants tend to grow upward, above the surface of the substrate.
IME, plants such as vallisneria benefit from a nutrient-rich substrate rather than plain gravel. In this case, the choice of substrate seems to make a difference.