“The constitution won’t allow it.”
Yes it does.
Article Four, Section Three:
“New states may be admitted by the Congress into this union; but no new states shall be formed or erected within the jurisdiction of any other state; nor any state be formed by the junction of two or more states, or parts of states, without the consent of the legislatures of the states concerned as well as of the Congress.”
In California the Legislature has lawfully delegated authority to the people in the form of the referendum.
That means that the California voters can approve this measure and then it goes to Congress. Congress at that point can decide the borders of the new states and fix any errors that are in the proposed map.
The key issue being that California wishes to divorce itself.
This is an opportunity for Congress to break up the power base in California by concentrating the San Francisco Bay Area and Los Angeles in one state, make San Diego a Red state, and put the food and water in another Red state.
Your analysis is correct. The rather uninformed knee jerk reactions of most are incorrect. The purpose of the proposal is in reaction to the far left wing influence of san fransico, los angeles and the coastal elites.