Look at how California has tweaked, tortured and twisted its electoral system to allow permanent, one-party rule. If it were simply a fact that “Californians are just more liberal” or “Republicans are disorganized” then at least you might expect a wider variety of candidates on the democrat side.
But there’s not more diversity of ideology in California, rather, government there is becoming increasingly uniform in thought.
All the key races are chosen through electoral fraud - and its a template for every other state as well.
If every conservative left Kalifornia during Trump the state would collapse by 2024. It might anyway, if a smart Republican publishes an "Indy Mac" equivalent regarding commercial mortgates.