I always get a good laugh when people say, "prove they could play with the big boys"
I mean lordy, we've been in a major conference for nearly a century, playing Nebraska and OU (and admittedly getting beat most of the time until Snyder came along and at least made many of those games more interesting, and even won a few. Really not much difference from the Big 10 where it was OSU and Mich and then everybody else for decades) and then Texas, and to a lessor extent Missouri, Colorado, Okie Lite etc. etc.
The Big 12 has the second highest avg coaches pay in major college football, and collectively has invested more into football infrastructure over the last 15 years than just about any other conference in the country.