You can't be a best of the rest conference if all the best programs aren't under your umbrella. And Memphis is the lynchpin in making that happen east of Texas. Individual teams outside of the PAC may pop up in a given year, but the PAC must have all of the best programs to rebuild their brand, get the TV deal they need, and to monopolize the G5 CFP bid most years. Landing Gonzaga was huge for their reputation as a conference and for the future accumulation of NCAA Tournament credits, which is significant money for programs outside the P4. Memphis views itself primarily as a basketball school, so the opportunity to compete with Gonzaga & SDSU consistently would be massive step up for that program.
https://twitter.com/HitmenHoops/status/1841464977590272417