You hit on the answer in the article. BYU is considered a teaching university and it is one of its major strengths. BYU graduates are sought after by graduate programs, medical schools and law schools. They understand that they came to BYU with strong academic credentials and they were taught by professors in the classroom.

Those universities that are designated "Research Universities" hire professors to do research as their primary function and teaching is secondary. They put a lot of money in that research and try to attract corporate dollars to match them. That is not to say that there is not a lot of research going on at BYU because the data tell you there is in fact tons of research being done. But some of those dollars that other universities seek are federal government dollars and they come with certain strings attached that BYU is not willing to accept. For that reason there are "research organizations" set up outside the university at BYU that can accept some of these funds without any obligation from the school.

BYU is also not a member of American Association of Universities because of the religious nature of the school. This group is run by professors and they view any limitation on freedom of thought or ideas, even if rooted in religious beliefs, to be censorship. BYU is on a list of 46 universities that are censored by the organization. Which proves a political point that liberals believe in free speech but only when you are agreeing with them. If you choose to say something counter to their interpretation of speech you are to be shunned.