"You can check out anytime you like, but you can never leave."
California has always been an important state for Notre Dame recruiting stretching back decades. In modern times, the annual series with Stanford was propped up so it could alternate with USC every-other-year to finish the regular season in California thus allowing the coaches to recruit the area immediately afterwards. Of course, Notre Dame could always send out coaches to California every-other-year for some extra pocket change compared to the overall recruiting budget, but it's always been an important selling point for playing Stanford when it really masks the fact that Notre Dame pretty much fell in love with Stanford as an aspirational peer back in the 1990's.