The ags were as happy as anyone else to dump the little sisters of the SWC and move to the B12. They were desperately trying to move to the SEC at that time but couldn't without Texas. Their revisionist history that it was mean old Texas that killed the SWC is... baffling. The modern economics of televised college football is what killed the SWC, and most certainly would have killed the B8 as well if the 4 SWC schools hadn't joined them to form the B12.
As for the B12, Texas didn't ruin it, Texas saved it. In the 2010 realignment it was Nebraska and Colorado departures that weakened it, but Texas propped it up and saved it by agreeing to equal revenue sharing and by pushing the media partners for better deals. In the realignment of 2011 it was the ags and Mizzou departure that weakened it, but again Texas propped it up. The proof is in the pudding, if Texas had REALLY wanted to leave, Texas easily could have. All options were open in 2011-- PAC, B1G, or SEC. Just as all options were open in 2021. It wasn't until the media contracts got so incredibly lopsided in favor of the B1G and the SEC that Texas knew it couldn't keep up by staying in the B12, that any decision to move was made. And geographically, the SEC made the most sense, plus it's the only place OU was welcome, and so the ultimate outcome was obvious. Plenty of us have been saying since 2011 that Texas was eventually going to have to join the SEC.
Anyway, TL;DR-- texags posters are dumb
They're going to be so disappointed when they find that the SEC is just an athletics affiliation and that Texas joining isn't going to change much of anything, other than scheduling among 16 rather than 14 schools. Oh, well, and the fact that they'll have to return to actually playing us every year and losing their accustomed 2/3 of the time.