Play two rounds at Hawk Hollow and tell me that's not exercise! Long steep hills...both ways!!!
I've mostly played courses in VA and NY and it's ruggedness definitely qualifies it as more than just hanging around at a BBQ. But this past Christmas I had the opportunity to play a handful of courses in the NW Arkansas and while they were fun courses, they just didn't have the elevation change. I easily played two rounds and didn't feel wiped out physically. I did feel worked tho. Still more than hanging out at a BBQ.
So I guess it's all relative to where you live. Tromping up and down forested hills or converted ski slopes is going to get the heart going. Walking thru the flatlands of our country will still get the blood moving more than standing around at a BBQ.
But in addition to moving through the environment we are also bending over and straightening back up several times. We fling things and force energy to move thru our bodies. We shout when we hit trees, or birdies.
We don't just work our muscle fibers, we work our eyes out also. From finding the right line, releasing on that line, watching the disc fly, and eventually searching for it in some deep schule. Image recognition keeps the mind sharp. Hand-eye coordination does too.
And then if you do play with others you are building social skills. And that gets you out golfing more often. So then, where does "exercise" end? It's not weight-lifting or x-country running. But it's not darts or chess either.
Whatever it is you're not going to get me to stop it.