Hey John,
Sorry for the late reply.
We had a non-ul > li structure in the first version of the menu and adjusted it based on community feedback:
As you can see, the thread has quite a lot of feedback and opinions. From our point of view, there is nothing against nesting non-menu items in a li since they are still part of the whole menu. This should also be unproblematic for screen reader users since you can always add aria labels, telling the screen reader to skip this part.
If you have a trustworthy source that sheds light on the subject in detail, we would be very happy if you share it with us 