If most people have a significant Vitamin D deficiency, then I agree that my comparison was absurd.

Probably heavily depends on the country/region, but here in Germany it is basically the norm to be Vitamin D deficient. Like, half of the population have a deficiency when there is some sun and basically everyone has a deficiency for months during fall/winter/spring. So I have to laugh when I read "taking vitamin D does nothing unless you’re severely deficient". Yeah like, but that's most people in many countries lmao

Without supplementation, yes, most people do have a substantial deficiency. There also exists the sufficiency range which is higher, and the optimality range which is slightly higher still.