I tried these and i learned that if you dont do things juuuuuuuuuuuust right, you will kill your seeds with them. Rock wool or some of those dry (coco?)pucks you saturate with water are much more reliable. They also seemed to grow very slow in them compared to everything else.
Root riots seem to work great for cuttings or if you grow long enough root to a seed between a paper towel first, but throwing seeds randomly on a ground seemed to be as reliable as these root riot cubes for germinating seeds by simply putting seeds in them(after ofc first tearing it open a bit more as the material is too thick and spongy for start of a plant to push through properly.
I have germinated tons of seeds in various ways and never had so many fail and i did try to do things juuuuuuust right with them. But again for cuttings that spongy texture seems perfect and cuttings seem to like to root in them. But never ever will i bury a seed in those fuckers again, i wasted like 60 dollars worth of seeds with them and there were different strains, so it wasnt because of bad seed batch either. If a seed has long enough tail, so that it can be placed in a way that the top is only a few mm under, then they will grow just fine.