working with some teachers here at Universidade Federal de Santa Catarina, Brazil, we have found that the fact of hidding the "group" and "grouping" availability conditions if there is no groups or groupings on the course is not the best approach and can lead to teacher thinking something may be wrong (they don't exactly remember of not having setting up groups yet).
So we proposed some changes to the interface at MDL-48183
As it is a matter of usability, Moodle team would like to know from us what we think.
There is a more detailed exposition of pros and cons on the tracker.
Any contributions are welcome.