I don't know how it looked in the 80's, but this is how it stands today:
BYU - 32% from Utah (
https://www.byu.edu/facts-figures)
Utah - 70% from Utah (
https://www.collegefactual.com/colleges/university-of-utah/student-life/diversity/)
Utah State - 72% from Utah (
https://www.collegefactual.com/colleges/utah-state-university/student-life/diversity/)
The environment in-state may be kind of sucky, but the picture looks different nationally. I live in Texas, and my co-workers (mostly A&M and Texas Tech fans) are all familiar with BYU, but they can't tell the difference between Utah and Utah State (they literally don't know they are two different schools 😂). I also know a dozen or so BYU fans in my ward compared to maybe one Ute and no Diary Utes. My girls wear BYU gear in public all the time and the only time they get comments are from fellow Cougs (who we come across a lot more than you'd expect).
I would love nothing more than for BYU to rebuild its cache locally in my home state, but they're definitely winning nationally, and it's not close.