@Broken Adam
You’re forgetting that the whole anti-pop/teen pop subgenre was pretty much dead by 2005 when the artists from that time either faded to obscurity or were starting to be more commercialized with the cases of Jojo and Ashlee Simpson. The only real pop singers from that time before Lady Gaga came were Kelly Clarkson, The Pussycat Dolls and Alicia Keys while the landscape shifted towards a more R&B and hip hop infused sound because of artists like Christina Milian, Ciara, Amerie, Cassie, Paula DeAnda, Kat Deluna and the like. Lastly, Nelly Furtado filled that gap temporarily when she reinvented herself as a club singer because of Timbaland before the sands really started to shift by the end of the decade.