What does "not limited to" mean in conference announcements

There are so many conference announcements that use the phrase

the topics of interests include but are not limited to

I honestly cannot understand why such phrase is used. The announcment already lists more than 20 topics and then declares that the topics are not limited to the listed ones. I have two questions related to this issue:

1. Why lot of topics are listed if they do not limit the topics of submissions?


2. Does listing these topics mean that the submissions about listed topics are given higher priority?