Beyoncé was the frontwoman of Destiny's Child, for whom she also wrote, produced, choreographed...just as Awards won by the group are considered to have been won individually by each member, it makes sense for their sales and stats to be attributed to her too. She did sell however many records, she did spend however many weeks at #1, and so on and so on. That wasn't someone else, that was her.
That said this particular record is for her first five SOLO albums...the other #1 albums she's had are just bonuses..