The lens runs from 70 mm up to 300 mm... even at three times the focal length at 70 m m you are at 1/210 second. At 200 mm, the old rule would be 1/200 of a second, and double the focal length would be 1/400 of a second, and three times the focal length would be a mere 1/600 second. As I said oh, I think there is some exaggeration going on here. We're not talking about people with palsy, but people who are actually trying to hold the camera steady, or who Avail themselves of a monopod tripod or other firm support when they must use slow shutter speeds
I think there is some exaggeration here about the through the viewfinder stabilizing that VR does, and in fact many times they are causes the viewfinder image to Jump Around, and does not quiell movement, but in fact exacerbates it. I have been using Nikon VR lenses since 2001 oh, and I'm not sure what you are talking about.
A few months ago I bought a 1988 version of Nikon af 75 to 300, deep curly on the focus model with the built-in tripod collar And the macro focusing range. I was looking at some snaps that I took with the lens handheld speeds as low as 1/15 of a second at 300 mm and I was quite surprised ... surprisingly Sharp.
The D3500 is a DX camera, so 1.5x crop.
so 1 / (FL x 1.5) = 1/450 sec, rounds up to 1/500 sec.
Double the speed for a newbie and you are at 1/1000.
As much as I agree with you, about using support, I've seen too many people using a long lens with NO support.
It is the exception that I see with a monopod and even less with a tripod. And the monopods are usually under the 70-200/2.8, 300/2.8 or 400/2.8. IOW heavy lenses.
To me that is similar to people holding a P&S or cell phone camera out at arms length, then they wonder why the picture is blurry.
OK, so we agree that we use VR differently.
I shoot field sports (football/soccer/lacrosse) with a Nikon 70-200/4 on a D7200.
In MY experience, VR stabilizes the viewfinder image, well enough to make it a LOT easier for me to hold the AF point on the subject.
I use single point AF, because I have to pick out ONE specific player in the several players close together, in the viewfinder.
I have tried with VR off, and it is definitely harder to keep the AF point on the subject, when the subject is bouncing around in the viewfinder.
When I shoot field sports, I am not in the max stability stance, that I would use for a still subject, like shooting a target rifle. Rather I am in a stance where I can track the moving players, like shooting trap/skeet with a shotgun. VR is important to compensate for my reduced stability in that stance.
BTW you and I are not a newbies.
15 years ago, I shot my niece's wedding, hand held (standing), a non-VR 70-210/4 lens at 210mm on a DX camera down to 1/30 sec. That was 3-stops slower than the guideline. It was a DIM church, and I was expecting 50-75% rejects, I got 80% keepers. I used every trick in the book.
We have that book and experience, the OP in all likelihood does not.