I would also venture to argue that the weightlifting swing came after either the GS or the HS swing, since we didn’t start to see weight lifting plates until the mid-20th century. Any heavy swing is going to have to be a hardstyle swing, doing a heavy swing GS style is not going to end well.
Plate loaded dumbbells and barbells existed at the beginning of the 20th century. Arthur Saxon's book, published in 1905, shows him using such equipment and demonstrating the dumbbell swing.
Also, the book contains ads for plated loaded barbells and dumbbells.
GS, as a sport, did not really develop until significantly after this time period. The kettleweights used by weightlifters were shot loaded. Russian GS was quite specific to Russia.
I also think you are selling the swing (and your training) short if you rely on on it as only a conditioning and grip drill.
The best results come from consistent practice, and making the best out of the swing is not a bad thing, but I think the emphasis on it is a little extreme. When all one has is a hammer, everything looks like a nail, but for athletic training, we have to be more critical.
I think barbell hip thrusts or glute bridges would be better than an extremely heavy swing, and barbell deadlifts, cleans, and snatches would be better for max strength or power.
Kettlebell training takes a lot of skill, and consistent practice leads to many results. However, I do not see kettlebell training leading to extremes, but results on many levels. That, I think, is the "selling" point of kettlebell training, that people can get stronger, leaner, conditioned, more mobile and flexible, and have fun with a single tool and training method.
Unlike many people, I started as a boy, when I was 12, with calisthenics and then to lifting iron weights. By the time I tried kettlebells, I could easily swing over 100 lbs, clean, press, and "snatch" the 24 kg bell (the heaviest one I had access too when learning), and at the time, the Turkish Get-Up was not in the Program Minimum so I never tried to do that. I did not, at that time, find kettlebell training to be particular challenging or that effective for my goals (in particular, I had to use a different foot position than my deadlift and snatch) and I could lift heavier weights than I could get in kettlebells and they were quite expensive at that time. So, I stopped after trying them. I did not enjoy them, and it took some time and practice to get the skills necessary to use them, when I could be lifting much heavier dumbbells and barbells.
Recently (a few months ago), I tried a Turkish Get-Up after looking into Strong First, and I could easily do them with a respectable weight despite having no instruction and some awkwardness in the unfamiliar movement (I have always trained on my feet or hanging from a bar). In hindsight, when trying out a new movement, I think it would be advisable to learn the movement before holding a heavy weight over one's face, as my focus was not on getting up, but on stability in an unfamiliar movement.
So, there are many ways to strength, and I think consistency is the key, and for those who do not have a necessity, personal enjoyment is very important.
And more recently, I have re-evaluated my goals as I am getting older (not "old", but looking more long term than immediate personal records), and have stopped all lifting of iron and focus exclusively on calisthenics and strand pulling.
For those who are curious why someone so much of an "outsider" of the StrongFirst community is here, when I was 15, one of Pavel's books greatly assisted me in overcoming some problems I was having.
Strength is for everyone and everybody will benefit from being stronger, no matter how one gets there.