It's a game of Dog eat Dog.
Aaliyah was the top female singer (in her genre) for a good minute but guess who was having a hard time getting inroads to be a superstar in her own right around that time? Beyonce.
I'm cutting out a lot of storyline to get to a point... Aaliyah died in 2001. How soon after did Beyonce really start to blow up as a solo artist? The industry just goes into purges and finds the necessary replacements, if they're worthy. Mind you, Beyonce has been FEROCIOUSLY protective of her spot for damn near 20 years..and there's been casualties (i.e. Keri Hilson, Jazmine Sullivan, etc..).
Only reason why Jennifer Hudson still bopping is because she gave up multiple family members and Clive Davis loves the hell out of her so they detoured her career for the most part from clashing with Beyonce's. Dumb ass talk shows, commercials and shyt.