When mongoimport, mongoexport, mongodump and mongrestore were rebuilt in Go in version 3.0, they could no longer link in in libraries from mongod and thus could not read/write from/to the files in the DBPATH without going via a running mongod.

For all four tools there is a comment/warning like:

"Changed in version 3.0.0: mongoimport removed the --dbpath as well as related
--directoryperdb and --journal options. You must use mongoimport while connected
to a mongod instance."

• https://docs.mongodb.com/manual/reference/program/mongoimport/#options
• https://docs.mongodb.com/manual/reference/program/mongoexport/#options
• https://docs.mongodb.com/manual/reference/program/mongodump/#options
• https://docs.mongodb.com/manual/reference/program/mongorestore/#options

This confused my customer with a sharded cluster who tried to bypass his mongos to write directly to a mongod for the shard ...

The comment/warning should be updated to something like " ... without going via a running mongod or mongos as appropriate."