The index management spec requires that the driver raise a client-side error if the commitQuorum option is specified when creating an index on a pre 4.4 server:

This option is only supported by servers >= 4.4. Drivers MUST manually raise an error if this option is specified when creating an index on a pre 4.4 server. See the Q&A section for the rationale behind this.

We should introduce this behavior to the driver.