Requirement to add landlord to insurance?

Here’s one I’m asking as a renter, though it’ll also be good to understand once we have rental properties: My annual lease renewal is coming up, and I’m now required to have $100k of renter’s insurance and to put the landlord on the policy. I have renter’s insurance for significantly less than that because I don’t have $100k of assets in the apt. But I’m really puzzled about having to add the landlord to the policy. What’s the purpose here? How likely are they to balk if I refuse? Is there any law around this (I’m in California)? I love my place but now have to evaluate whether I want to live with this requirement.