Heck, the suggestion was probably motivated as much by my own nostalgia as anything.
In my early teens, I lived on a tiny lake in southern New England, and we used to sleep out on a small floating dock on some summer nights, ostensibly to fish for bass just as the sun came up. We did that, all right, but I don't think that was the real reason for sleeping out.
In my late teens, I was in a different area, but again southern New England. By then I was a dedicated backpacker, but I couldn't afford to get out on the trail nearly as much as I wanted to, so I'd go for quick hikes several times a week in an area of forested ridges and lakes. I got to know the trails so well I could tell when a single other person had been down them since the last time I had, and in times in the spring and fall when it wasn't too cold but the bugs weren't bad, I'd go out alone and sleep in the woods just for enjoyment.
There was one particular spot I went every time, in deep, dark, quiet woods where the trail paralleled a gurgling brook. Becuase there wasn't much sunlight under the canopy, there was little underbrush to deal with, and it was just beyond where a field of wild lady slippers (American orchids) bloomed every year. I'd go out there and spread a tarp for a groundcloth in the ferns, read a book in the late afternoon light with my back to a pack leaning on a tree, and I'd sleep that night with just the tarp, a light down sleeping bag and a foam pad.
Just sitting there and reading, I found if I stayed still and quiet enough, for long enough, the woods would slowly come alive around me. It was there that I saw bright-colored woods ducks for the first time, swimming on that little creek in the fall. Once a raccoon passed within 10 feet of me while I was reading, seemingly unconcerned. Very near there that I had once seen a Great Blue Heron, and there was a small golden-colored fox who lived somewhere nearby. I spotted him a few times, but one time in particular he didn't see or hear me, and when I saw him he was playing in a sunbeam that cut down through the darkness of the woods, alternately chasing his tail and the bugs that became visible when they flew through the light.
I always had contingency plans in the back of my mind- it was something between two and three miles away from the house (by the trails, probably much less "as the crow flies") which wasn't too far to walk if the weather turned really bad, but I also knew where there was a rock overhang that formed a small shallow cave in a ridge only a quarter of mile away. It was cramped there- I couldn't stretch out or stand- but it stayed pretty dry even in the worst rain. I had sheltered there before on day hikes, when I'd get caught by a thunderstorm.
I never had to bail out on an overnight there, though- I didn't do that many overnights, but I never had to deal with more than a moderate, gentle rain in the times I did, and for that I just pulled the tarp over the sleeping bag and myself.
After I wrote that earlier message I was trying to remember how long it has been since I slept outside without a tent. I know it's been far too long. It seems like I think about these things in the deep of winter when they're not feasible, and then when spring comes I'm always too busy with trivial things I won't remember one year later, much less in decades. I hope I'll get out more this year.