What's the security risk of enabling client sharing services?

If a network device needs to send data to another network device on the same LAN, it addresses the outgoing packets based on the destination device's MAC address.

Assuming the default settings for OS X, a standard user can only configure directly attached or local network printers from the Print dialog. Also, the appropriate drivers must be installed before the standard user configuring the printer.

Any application that supports Auto Save and the Finder can manage document locking.

If a client sharing service is compromised, an unauthorized user can control your Mac and execute unwanted applications or processes.