I think this is a pivotal issue, but needs subdivision to maintain focus and answer instead of begging questions.
1. All this "unused oxygen in circulation"...does it constitute a medically meaningful fraction and partial pressure, especially versus CO2, vis a vis actually maintaining life as we know it? Does CO2 build up in that fraction when the pt isn't EX-haling too? (Remember, CO2 isn't just a suffocator, it is a toxic waste product as well).
2. What is sold to otherwise untrained bystanders, or trained first-aiders, first responders, EMTs and so forth do not all equate because of differing training in airways, means of inflation, drugs, monitoring, use of laryngoscopy and suction and such. Apples to oranges, or at least plums to pluots.
Example: we regularly teach laypersons to extend the neck by raising the chin to open an airway (which can cause a lethal cervical dislocation), but teach professionals and first responders the jaw thrust (when that can exacerbate facial trauma and thus lose airway), EMT-Bs get supralaryngeal airways (which can tamp airway obstructors into the larynx), paramedics to to intubate, etc. They do not equate. We will accept a degree of mortality and morbidity when to do so will pose risk acceptable due to the alternative (hands-only and without resuscitation, versus none at all).
3. The free oxygen radical injury, has it been clinically tested? Just as betadine and peroxide, known to harm tissues in vitro and with overuse, can prevent or reverse important infections, can it be that oxygen, may in vitro or with overuse cause damage (to what degree?) later, but immediately provides the chance of there being a "later"?
While I agree that "Kompression is King", I still believe judicious scientific airway and oxygenation are potential tools, and they are tie-breakers in the small percentage of cases where field resuscitation is actually going to work (i.e., cases without irreversibly lethal infarct, traumatic asystole, or prolonged periods without respiration/circulation before discovery possibly excepting hypothermia/mammalian diving reflex cases) .
The inaugural hallmark of the EMT-P or A, the spine board, was inflated into a harmful panacea without or despite real clinical results, then demonized the same way. One aspect of the mind of a technician is to try to over-simplify expansion or retraction of the uses of his permitted tools.