These were enormous, decade-long studies. The qualifier is perhaps a poor description -- vitamins offer no benefits outside specific, diagnosed vitamin deficiencies. So unless you think every one of the 100,000 nurses ate properly, yes, they are indeed saying your McDonald's and hot dog and macaroni and cheese diet is fine (vitamin-wise).
No differences in disease onset betweem the two groups, ergo useless. This is also how they fpund out silicone breast implants were actually safe, in spite of fraudulent lawyers driving Dow into bankruptcy because they could FUD juries. No difference (aside from immediate rupture effects) between implants and not. And specifically, onset of things like arthritis, joint issues, and autoimmune things, lupus, etc. No difference in rates.