Even for influenza, treatment most definitely affects adverse outcomes...

See this paper about impact of tamiflu on hospitalized patients with influenza.

But for COVID-19 we don't have any proven _specific_ treatments...we do have effective _supportive_ treatments, e.g. oxygen or ventilation. I can assure you: if you are unable to effectively oxygenate your body because of viral pneumonitis. Having oxygen therapy (no specific therapy, but supportive therapy) will make a huge difference in outcomes.

tb