This experience sums it all up right here.
By default, with all iTunes and Quicktime installs, Apple installs its BonJour service on your computer:
"Bonjour, also known as zero-configuration networking, enables automatic discovery of computers, devices, and services on IP networks. Bonjour uses industry standard IP protocols to allow devices to automatically discover each other without the need to enter IP addresses or configure DNS servers. Specifically, Bonjour enables automatic IP address assignment without a DHCP server, name to address translation without a DNS server, and service discovery without a directory server."
Sounds neat don't it? Except there's no control over this thing. This "automatic discover" service is fine and dandy on a home network. But on a corporate network? It has the potential to cause all kinds of grief.
Why? Because its unwanted Broadcast traffic. Broadcast traffic goes to all devices on the same network. Broadcast traffic has legitimate purposes for advertising what machines are hosting what services on the network.
So the Bonjour service talks to all devices on the network, looking to share media. Even if they are a printer, a PLC device or whatever. In a worse case scenario, if a malformed packet comes from the Bonjour service it could shut down a manufacturing line by corrupting a PLC device. (This is why your IT department gets all in your face when you just start doing stuff in the office. REALLY bad things can happen).
On another front, even if its not corrupted, it creates traffic, takes up bandwidth. Enough computers on the same network subnet (or broadcast domain), and you could get congestion causing service outages.
Apple, and they do this all the time, takes the option of control away from the end user and/or the corporate network administrator. That company has this mindset that everything they do is perfect. Don't blame them, all the problems are your fault.