Their goal was to sink BYU sports. The way to do that was a) cancel future competitions, b) dominate current (at the time) competitions, and c) win over disillusioned BYU fans.
They did a decent job at A and B, but their execution was done in such a petty way that almost no BYU fans saw Utah as an alternative to a waning BYU.
The tone of the school and athletics department toward BYU was insufferable.
In other words, Utah couldn’t help but be Utah. Nobody who didn’t grow up cheering for trash was going to change their mind and cheer for trash later in life.