Not sure what you're confused about, and OP was talking about legal immigration.

Prior to 65 immigration act, California was over 90% white.

By 2010, non-hispanic white was down to %40, hispanic ~%37%.

That is a huge demographic change. Hispanics nationally vote for Democratic/liberal politicians on avg. 70%.

So.. ergo, the dramatic blue turn California has taken politically can be accounted for by drastic change in demographics.

Your first statement is just restating the same premise: a dramatic change of the makeup of the electorate (whatever their "needs" or preferred political policies) changed the outcome of elections.

https://en.wikipedia.org/wiki/Demographics_of_California

section: "Population of California according to racial/ethnic group 1960–2010"

After Prop 187 about a million Mexican resident aliens got their citizenship. That also coincided with a hard turn towards fascism by the Republican party under Gingrich.