BYU does enough research to be "R1" or "Research 1". When we do tenure and promotion, we only accept letters of external review from R1 institutions. Realize that the following are "Research 1" institutions:
Cincinnati
Colorado State
Hawaii
Nevada-Reno
North Texas
etc...131 universities total.
BYU publishes more research than many of these schools.
The reason why BYU is not officially categorized R1 is because BYU doesn't chase grant money (instead often funding research internally) and doesn't have many doctoral students (instead doing research with undergrads).
So both things are true: BYU is a research university but not technically an R1.