Yes, that is the reason.
Democrats have the population centre and they’ve created policies to drive out wealth creators, leaving Republicans, who still outnumber Democrats, but are too spread out to be able to do anything about it.
I think Jonty30 references the largest parts of the state
that are run by Republicans. (or they used to be, things
are changing). It may seem (or more accurately, used to
seem) that most of the state is Republican based on this
land mass evaluation, but the fact is, 46% to 24% of the
state’s citizens are registered Democrat/Republican.
Let’s see what I can find on all this, linked below.
See mapping political geography: One quarter page down...
https://www.ppic.org/publication/californias-political-geography/
See Report of Registration breakdown...
https://elections.cdn.sos.ca.gov/ror/15day-presprim-2024/complete-ror.pdf