Why fieldset as .form-group instead of div's?

Created by: radek-anuszewski

Hi!

In Components / Forms / Form controls I noticed that "form-group" class is on the "fieldset" tag, instead of "div" like it was earlier. I thought that fieldset is meant to group few controls in one group (like group weight and growth in one fieldset called BMI), not for single form control. And radios are not grouped with fieldset tag - but I found on Mozilla Developer Network and H71: Providing a description for groups of form controls using fieldset and legend elements that radios should be wrapped in fieldset tag. Why fieldset tag is used instead of div's, which IMO is incorrect (of course I am not 100% expert :) I only place here my thougths) or am I wrong about it and it should be as is in docs now?