they generally dominate, even compared to other P5 conferences. And it’s not even close. Of course those aren’t the high-profile sports, and the label exposes the conference to ridicule when things go south in football and basketball. But that’s the origin of it.
And no, your friends in AZ shouldn’t take pride in it as the AZ schools don’t have a lot to do with all that success. It’s primarily Stanford, UCLA, and USC, the only three universities in the country with more than 100 national titles.
WikipediaThe following is a list of current Pac-12 Conference members' NCAA and AIAW championships. The Pac-12 was the first conference to win 500 team titles & currently (As of December 15, 2018) Pac-12 members have won 517 NCAA national championships, which is 215 more than the next closest conference, The Big Ten. Since the 1999-2000 academic year, the Pac-12 claims a total of 150 NCAA team titles, including 10 in 2013-2014. They have also led or tied the nation in NCAA Championships in 48 of the last 54 years, the only exceptions being in 1980-81, 1988–89, 1990–91 and 1995-96 when the conference finished second, and finished third in 1998-99 and 2004-2005.
https://en.wikipedia.org/wiki/List_of_Pac-12_Conference_national_championships[https://en.m.wikipedia.org/wiki/List_of_Pac-12_Conference_national_championships]
WikipediaListed below are the colleges or universities with the most NCAA Division I-sanctioned team championships, individual championships, and combined team and individual championships, as documented by information published on official NCAA websites. Excluded from this list are all national championships earned outside the scope of NCAA competition, including Division I FBS football titles, women's AIAW championships, equestrian titles, and retroactive Helms title nominations.
https://en.wikipedia.org/wiki/List_of_NCAA_schools_with_the_most_NCAA_Division_I_championships#NCAA_Division_I_Team_Championships[https://en.m.wikipedia.org/wiki/List_of_NCAA_schools_with_the_most_NCAA_Division_I_championships#NCAA_Division_I_Team_Championships]