[NorwegianDude]

They usually isn't used as the primary means of propulsion on most bigger ships. It's also not uncommon for them to be retractable. If you need a large ship at a very specific position for a week, then you definetly need it, and that is a common use case as it allows for impressively accurate control. Heck, you could avoid moorings altogether and just keep it in place without it if you wanted to.