[docs] Improve Pickers accessible DOM migration section description (m…

…ui#15596)

docs/data/migration/migration-pickers-v7/migration-pickers-v7.md

@@ -70,10 +70,13 @@ Feel free to [open an issue](/~https://github.com/mui/mui-x/issues/new/choose) for
 
 ## New DOM structure for the field
 
-Before version `v8.x`, the fields' DOM structure consisted of an `<input />`, which held the whole value for the component,
-but unfortunately presents a few limitations in terms of accessibility when managing multiple section values.
+Before version `v7.x`, the fields' DOM structure consisted of an `<input />`, which held the whole value for the component.
+Unfortunately it presented accessibility limitations, which are impossible to resolve.
 
-Starting with version `v8.x`, all the field and picker components come with a new DOM structure that allows the field component to set aria attributes on individual sections, providing a far better experience with screen readers.
+Starting with version `v7.x`, we have introduced a new DOM structure that allows the field component to set aria attributes on individual sections, providing a far better experience on screen readers.
+This approach is recommended in [W3C ARIA](https://www.w3.org/WAI/ARIA/apg/patterns/spinbutton/examples/datepicker-spinbuttons/) example and is also used by native date HTML input element under the hood.
+
+Starting with version `v8.x`, the new DOM structure is the default for all fields.
 
 ### Fallback to the non-accessible DOM structure