If anything the problem is that the floodgates are open and everyone and their mother feels the need to upload baby’s first Blender model, which makes good products harder to find and causes race to the bottom economics, which makes it unsustainable to produce professional quality content.
If they are actually able to sustain professional content production on marketplace revenue, then that is great. However, I find it more likely they are simply porting existing content to UE4.