I have a single speed bicycle for sale - yes, I know there are 5 sprockets things on the rear wheel but the control cable is cut and tied to the saddle for YOUR SAFETY.
There are other bicycle owners who are using the same high quality 5 sprockets to save time and effort, so should you desire you can get extra tools and tinker to get full use of the gear system - saving you effort and time. But you would be voiding all and any guarantees and warranties offered.
And just possibly: Because the 5 sprocket system was designed and built for average 'use patterns' you may be reducing the expected life of the gear system by only using one sprocket when travelling to wherever you are trying to reach. I have no information on that but the price does include a contingency.
Remember, all limitations and price differentials are for your own good :)