I think the gap you have is in understanding that Podman Compose was meant to line up with the limitations of docker's compose, but technically is more capable.
Quadlet files let you do more complex workflows like deploying multiple copies of a service in your deployment that regular compose doesn't, while not running full kube.
The use I have is that I have something deployed in compose right now that I'd like to scale up on the box since i have the capacity for it, but dont want to deal with a full kube setup or the politic
Personally I've converted most of my single node k3s to using quadlet files instead as its less fragile. I absolutely deploy single containers in the quadlet. They show up in journalctl and the ergonomics are great.
This reminds me of when I was planning out a tubular bells project. there is an amount of crankery around various notes and I came across a series of videos about the various Cs and their use in healing or chakra alignment.
When i went to buy some tuning forks I noted some more weird mysticism, but hey at least they produced a nice set of C notes.