From a New York Times Magazine interview in 2003. Emphasis added.
JACK: It’s not counter to us. It’s what our band is about. We’re white people who play the blues, and our problem was how do we do that and not be fake? Our idea was to strip away everything unnecessary, to put ourselves in a box, to make rules for ourselves.
What sort of rules?
JACK: In live shows, we never play from a set list. The last record, we said, no guitar solos, no slide guitar, no covers.
And no bass?
MEG: The last record had no bass. This one has some bass. We’re not against the bass.
Why hem yourself in with restrictions?
JACK: It makes the band what it is. I’m disgusted by artists or songwriters who pretend there are no rules. There’s nothing guiding them in their creativity. We could’ve spent six months making our last album. We could have recorded 600 tracks. Instead, we went and made the whole album, 18 songs, in 10 days.
And, from an editorial written in 2011, Why Meg Matters, after the band broke up. Again, emphasis added.
But just because Jack was the primary creative force in The White Stripes doesn’t mean Meg was inessential. I’ll quote Jack himself, from an interview I did with him just before Icky Thump was released:
AVC: Does a White Stripes song have certain parameters?
JW: Oh yeah, lots of them do. There’s an overall structure of simplicity, and it revolves around Meg’s drumming style. And it can’t be beat. We can’t do those structures in The Raconteurs. We couldn’t do them if we wanted to, and that’s the beauty of Meg. In The Raconteurs, there’s so many more components, so many more personalities involved. If you get another person in the room, you’re dealing with something else. It’s a different kind of collaboration, you know? The parameters of The White Stripes… you know, 70 to 80 percent of what we do is constriction, and the other 20 to 30 percent is us breaking that constriction to see what happens.