Iodine deficiency is still potentially a real problem, if you avoid seafood, iodized table salt, and iodized dairy (not all countries have iodine in dairy, and "organic" dairy doesn't). An example is teenage girls in the UK, who often choose restricted diets, and where they don't iodize table salt. It results in babies with cognitive deficits.
So if you're, say, a vegan whole foods shopper who only uses non-iodized salt, you could manage to get iodine deficiency.
https://www.nursingtimes.net/roles/childrens-nurses/lack-of-iodine-in-teenage-girls/5028525.article
"Re-emergence of iodine deficiency in Australia"