I stated they have never won the NCAA tournament, which is fact. I'm not diminishing BYU in the slightest.
You asked, "What exactly has utah done, which BYU pales by comparison, in bball?"
And I gave you my list. Utah's tournament success far exceeds what BYU has accomplished in its history. Utah has 150% more sweet sixteen appearances (heck, Andre Miller has half as many sweet 16 appearances than BYU does in its entire history). They have four more final four appearances. More top 25 rankings, more conference titles, more wins (closer than most would think), etc.
As I stated previously, BYU fans saying that they have similar history in basketball is like Utah fans saying they have similar history in football.