[en] Providing Accessible Names and Descriptions

just curious why:

This article strongly pushes _Rule 2: Prefer Visible Text_ and _Rule 3: 
Prefer Native Techniques_ (which I totally agree with) but then in 
theAccessible Name Guidance by Role table, radiogroup guidance is to use:

  * Use|aria-labelledby|if a visible label is present, otherwise
    use|aria-label|

rather than fieldset/legend?

thanks...