Powerlifting doesn't teach you the technique and spotting required to walk backwards down a staircase while holding a stretcher above your head so that grandma, who is in extreme pain, doesn't slide off and tumble to the bottom.
Neither does firefighting. The point is if we don't need as many firefighters to fight the fewer fires we have, there are more cost-effective ways of maintaining a group of first responders for medical emergencies.
You must be enthusiastic about people using ERs when they have strep throat, right?
Let me think for a few seconds about ideas. Fitter EMTs who can assist people in more demanding physical situations. A subset of firefighters who can provide medical assistance but don't need the complete fire training curriculum and so can be paid less. Maintaining the ratio of firefighters and stations which was previously found satisfactory but adjusting it for requiring fewer of them since we have fewer fires.