I seriously doubt you can substantiate that assertion. The US Constitution is mute on the matter of regulating insurance within the states (as it should be, as to prohibit such a measure would be a usurpation of power to regulate commerce within the states). So please show us where this provision is prohibited in the California Constitution.
Strangely, there are those in the industry that are clamoring for this as more efficient. They hate having to get something approved for sale in 50 different jurisdictions!
But Congress repealed another post depression act in the Clinton years that kept banks and insurance operations completely out of each other's arenas as well as investment bankers and stock brokerages. All three were separated to stop the collusion. Now it's beginning to return but nobody cares.
Who cares about any of these old laws brought on the the crash and depression? Afterall, we've got Waxman and all the Damnocrats to legislate and tax our A$$es off!!!
WaaaaaaaaaaaaaHoooooooooooooo!!! (Slim Pickens in Dr. Strangelove)