They certainly are retrofitted, but the existing semantic tags are largely abandoned for div soups that are beaten into shape and submission by lavish amounts o

They certainly are retrofitted, but the existing semantic tags are largely abandoned for div soups that are beaten into shape and submission by lavish amounts of JS and a few sprinkles of CSS (and the latter often as CSS-in-JS). For microformats there is at least a little ecosystem already, and the vendor-driven committees don't need to be involved.