That is a strawman. RNA is more complex than DNA because it can perform enzymatic reactions. Although you are correct that less is understood about how it all works, because we are just now discovering miRNA’s, and the role they play in post transcriptional regulation of genes.
The fact that this RNA mechanism can act as a transcription factor IS a supporting data point for the “RNA world” hypothesis, because something like this would need to exist in order for there to be any sort of a complex ‘all RNA’ replicator.