If you just want to share some folders on an existing Windows computer with the network without having an entire other system running then fair enough. But you've got the additional load that pieces on it while you're using it for other purposes
If it's a dedicated computer then Windows and in fact any operating system with a full GUI is overkill
Setting up a dedicated server can require a little extra effort initially, but once it's up and running you can almost forget about it, it's worth the effort for a less resource hungry and more stable system
If you just want to share some folders on an existing Windows computer with the network without having an entire other system running then fair enough. But you've got the additional load that pieces on it while you're using it for other purposes
If it's a dedicated computer then Windows and in fact any operating system with a full GUI is overkill
Setting up a dedicated server can require a little extra effort initially, but once it's up and running you can almost forget about it, it's worth the effort for a less resource hungry and more stable system