...for some reason.

Consider the hypothetical where the PAC12 reaches out and takes even a bad selection of 4 from the Big 12.

Let's say Kansas St, Oklahoma St, TCU, Texas Tech. Now the Big 12 is left with Iowa St, Kansas, Baylor and West Virginia. So then the Big 12 needs to get to 10 (at least) so takes on something like BYU, Boise St, Memphis, UCF, Houston, Cincy, SMU, USF.

And now you have a conference of
West: BYU, Boise, Kansas, Iowa St, SMU, Memphis
East: UCF, USF, Cincy, West Virginia, Houston, Baylor

And we get to play a 8 game conference schedule of

@UCF
West Virginia
@Houston
Memphis
@SMU
Iowa St
@Kansas
Boise

which is basically the AAC with BYU, Boise, Iowa St, Kansas, West Virginia and Baylor added.