Many of us say we don't trust centralized systems, don't trust governments, don't trust banks, and we choose bitcoin to protect our assets from the plunder of centralized systems. But today we rely on a centralized legal system to protect our bitcoins. Does that make sense? 
If you create a multi sig wallet and you spread the private key to many third parties, it's technically still decentralized. But, if you give the exact seed phrase + passphrase of your wallet to third party, then yeah you ruined the decentralization of Bitcoin. Although there's a service who offer inheritance plan, it's actually centralized because you have to trust them.