There are a bunch of policies that are useful for testing ( https://www.chromium.org/administrators/policy-list-3 ) that can not be set on the command-line and are somewhat convoluted to set up on the different OS platforms (and not possible on Android or Chrome OS without an external policy server).

A recent example is support for disabling translate which used to be a command-line option.

It would be very useful for external tooling to be able to set the policies remotely over the dev tools remote debug protocol.