Your lifestyle could determine if you must have a desk in your home or not. Are you organized? Is there a place for everything and everything in its place? Where do your monthly bills get put? A desk would be a great place to file them every month so come tax time you would have everything in one place. You could have a file for items to be paid and a file for those that are paid.
The style of desk will determine which chores can or cannot be done every month with the piece of furniture. If you have one that is for a computer there may not be a place to do any other work. It may only be for a place to put your monitor and computer paraphernalia. You will do well if there is also a place to write in case you want to take notes while you are on the computer.
Most homes these days have a desktop computer and a desk to place the monitor on is almost an essential. You can use other places to put the monitor but it may not be as comfortable as having the proper set up that a computer unit would give you. Some of the computer desks are adjustable for heights to make them more comfortable to sit at. However they may not offer the extra space for writing and doing other office duties.