Muddiest Point from Sept. 30 Class

I'm a little confused about the review before the lecture about MARC being replaced with a new system, which I know nothing about- Shouldn't we be learning more about it? Also, it was discussed that we as students- who are about to enter the field, we don't need to know how to manage and create databases but only know how they work conceptually. I just don't understand then what I should be focusing on gaining from the lectures now.