Often yes. But also blockchain's can be useful simply for backups and scaling: by cryptographically linking every bit of data together you can be confident that you actually have a complete copy without any errors.

Git is basically a blockchain for this exact reason: starting from a git commit hash, git works backwards, checking that every byte of data is what it should be. Similarly, modern filesystems like btrfs use strong (if not cryptographically strong) hashes for this same reason.

Though in a sense, you're still correct: the "actor" you aren't trusting here is your own computer hardware.