1) BYU fans mocked Utah fans for thinking they had a chance at either. BYU perception of Utah is not consistent with the rest of how CFB sees Utah. As a result, it's hard to take BYU fans and their subjective perspective seriously.
2) Utah insiders / alum / coaches were vocal about invites being imminent long before they became a reality. So many Utah fans were speaking from well grounded sources on both invites. BYU fans were speaking off their own assumptions about Utah as a program.
3) Part of the disconnect is BYU fans don't really understand alignment. Never have. In 2010, it was about cable subscriptions and adding new markets and adding more compelling games. The 2010 P12 invite in particular, was about rounding out numbers and creating the CCG.
The presidents did not like Utah. Larry Scott did. Utah had to sell everything they could to get accepted. Without BCS success / Final Four success...Utah had no chance. So it was a huge factor.
For the Big 12 alignment last year, it was about survival and replacing TX and OU. This year, it was about eliminating the P12 and narrowing the gap between P3 and P2. BYU fans thought it was all about cable subscriptions and markets like 2010. It wasn't. FOX/ESPN already have penetration in every US market. There is no B12 network needing adoption. This go around in general, as we see for P2 alignment, was about following the NFL lead and creating more must-see, big TV games each week. A school like Utah that is perennial top 25 that has reached the top 10 more often than not the last decade or so...is a great fit for any P 4/5 conf outside P2.
Utah narrowed the perception gap between B12 and P2 better than any other realistic candidate. Including CU, ASU and AZ.
4) On your last point, Utah has been nothing short of dominant against the collective south the last 3-4 full seasons. Credit AZ for a big win, but they have a long way to go as a program to close in on Utah. that starts by hoping they keep their coach and QB.