The argument is presented visually in this video:
https://www.youtube.com/watch?v=ebyxrDRMx0w
The relevant part starts around 15:45, but the gist of it is that storing and copying data is not free, the pressure of this cost is proportional to the complexity of an organism.
So the argument is that this pressure does not allow the accumulation of longer nucleotide sequences, so you cant' get evolution started based on a relatively short piece of RNA or DNA.