If only badblood's first week was counted

Why didn't Billboard start and end the chart two weeks earlier like they've always done before? They've always started Memorial Day Weekend and ended Labor Day Weekend. If they really rearranged the weeks for one song, "Bad Blood" as someone suggested, that's simply a sign of sheer stupidity on part of the publication.

Someone said Billboard shifted the chart forward two weeks this year simply to exclude Bad Blood's week at #1. I don't know if that's true though.