in the grand scheme of things both expose you to very similar risks, ratio spreads are risk-capped one sided, short strangles/straddles expose you on both sides. It is a horrible way to trade options long-term, in fact I have not seen a single options trader who survived with such approach alone. Most who sell premium are very good at protecting themselves at the wings when it is needed.
It is selling short calls and puts on the indexes whereas spreads involve a long and short side and trader might sell more puts than calls but not sure what ratio if any. These are pure naked trades I believe.