This is true, but sort of a sleight of hand -- obese people that don't exercise have more muscle mass than non-obese people who don't exercise, just to carry around all of the fat. And obviously the average American, both male and female, is more overweight/obese than in 1924.
(I agree with basically everything else you say, though.)
What I could have added was a caveat that sample non-obese people from each time would indicate that 2024 people have greater average muscle mass.
Personally, a more interesting question is whether growth along the Kardashev scale leads to a greater disparity in muscle mass vs body fat. The past 100 years would seem to indicate that it is possible. That being said, it could also be a uniquely American phenomenon. My hypothesis would be that avg muscle mass among French men has still grown over the past 100 years but I don't think obesity has grown to the extreme that it has in the USA.
https://jamanetwork.com/journals/jama-health-forum/fullartic...
And relative they are weaker in the sense that the ratio between strength and body mass is smaller than that of normal people.
And then we have the powerlifting community.
You make one specific relevant claim: "obese people don't have more muscle." (Which belies everything I've read on the subject.) So, uh, why do you think that?
Not true. Overweight and obese are defined on fixed scales. You can have a population that is 100% obese.
No? You have to compare like for like. Sedentary obese women have more muscle mass than sedentary normal-weight women, and sedentary obese men have more muscle mass than sedentary normal-weight men. (And the ratio of women to men hasn't moved very much since 1924, and both sexes are heavier than they were in 1924.)
The rest of your comment is not responsive to mine.
I think the former is uncontroversial but boring, and the later is wrong. I also think that people conflate the two because they want to pretend that being average is the same thing as being healthy.