In mongodb/mongo-php-driver#967, a user noted that libmongoc 1.9.4 silently ignores the writeConcern option that PHPC 1.4.4 may send to mongoc_client_write_command_with_opts() for commands other than findAndModify. In libmongoc 1.10, 5c88fde for CDRIVER-2214 added logic to raise an error if a writeConcern option was specified for alternative write commands and the server's wire version was < 5. This ignores the fact that the insert, update, and delete commands have historically supported a writeConcern option since they were introduced in wire version 2 (see: wireversion-featurelist.rst).

libmongoc does not intend for mongoc_client_write_command_with_opts() to be used for insert, update, and delete commands and mentions this in its documentation. We should do the same.