So I went on a historical 18th century ship reproduction and the crew was telling me that the ship could only dock because it had a modern motor. They said that historically it would just anchor off the dock in the water and would get supplied/people brought aboard via barges and boats coming out to it.

I was hoping someone could expand on this for me. Why would ships not dock at a port? Was this just impractical? Was it done at times if needed? I figure the boats needed to be launched from a dock/shipyard at some point so it wasn't impossible for it to do so.