You may be right. I think when people ate more in tune with the seasons people ate more cold water fish but thats less so now and while the D recommendations were upped I think a lot of people don't pay attention to.that type of thing and many people still have a D deficiency. However like a lot of things it can be oversold. CBD being one example. I took 5 to 6000 IU D3 a day for close to 20 years and attributed it to my never having a flu but I stopped for a few years and still didn't get a flu so who knows. I started taking 5 to 6000 IU a day again when corona came around as a precaution and because many recommend it. I live in a northern climate and it's hard to get much sun in the winter.