People are confusing fake it as a load gen or benchmarking tool.
"Why can I only put in XYZ documents per second into Couchbase with fake it."
On the Read.me file could you put a disclaimer that fakeit is a sample document generator not a load gen tool and create a link to Couchbase pillowfight for load gen.
https://blog.couchbase.com/performance-testing-load-testing-couchbase-pillowfight/