Why not just call Report Member Selections the report POV?

All POVs allow a single member to be set for a dimension. Report Member Selections allow multiple members to be set for a dimension. If multiple members or member selection functions resulting in multiple members are set for a dimension, the report in the book is run for each member. If multiple members or member selection functions resulting in multiple members are set for multiple dimensions, the report in the book is run for all combinations of those members. Just like a grid is generated for each combination of the members on the page axis in a report, a report is generated for each combination of the members set using Report Member Selections in a book.