Universal Print can't replace a print server entirely until a shared computer can be set to have a specific Universal Print printer be the default printer for all users on that computer. Without Universal Print, this is achievable in Group Policy Preferences Printers with loopback, which is commonly used for shared computers.
K-12 computer labs are only one example, basically any shared-computer environment where documents are printed for immediate use could benefit from this.
Think packing slips in a packaging shop, bills of lading in logistics, anything else that is high volume one-after-another (where badge/QR release follow-me printing is not viable) and you always need it on the printer right next to the computer you're logged into - regardless of who you are, and where you printed yesterday.