The self-cleavage of RNA by 2'-OH is a chemical textbook fact. The 2'-OH group has the proper position and orientation for a nucleophilic attack on the phosphate bridge. The kinetics of the reaction is greatly favored by the 5-membered ring structure of the resulting cyclic phospho-bisester. The length of the RNA molecule is not relevant since each nucleophilic attack causes destruction of the chain. The effect should not be confused with the length-dependent “error catastrophe” of accumulating mutations of RNA. Incidentally, some anaerobic ribonucleotide reductases are ancient, while others (aerobic ones) are later inventions.
I have only a few comments, which might improve the manuscript.