>>/46418/
I agree with you about them not being like regular off-the-street fatsos, especially when talking about the top-tier competitors that you mention. But what I say is that to me many still look like the unhealthy kind of fat. For example when I just search random images about sumo I find stuff like the pic I posted above.
I tried overlaying a plot of the "body-mass index" (BMI = weight/height^2) on the 30-years chart. According to random strangers on the internet:
BMI _ Classification
< 16  Severely Underweight

[16, 18.5) __ Underweight
[18.5, 25)  Normal
[25, 30)  Overweight
[30, 40)  Obese
> = 40 ___ Severely Obese

In the pic there are 2 curves: red is BMI=30, purple is BMI=40. Thus the purple-shaded region is "severe obesity", red-shaded is "obesity". The only area below BMI=30 is the upper-left corner shaded in light blue.
Now, I understand that this is just one rough measure, that it doesn't distinguish muscle from fat, and that sumo is a very niche discipline and thus this metric is possibly not the most apt for it, but it should help clarify my PoV
Perhaps one should try to compare this to another sport with "heavy" competitors to get a more balanced view. Maybe rugby