There is a huge difference between a router that has 2 or 3 ports, serves a dozen clients, and has to handle a few Mbit/second (typical household), and a router that has a few hundred ports, serves a few hundred clients, and has to handle many Gbit/s. There is also a huge difference between a site that uses a single router, which is managed by logging into a shell, and a site that uses hundreds of routers, with a management framework.
At home, my FreeBSD box is router, NAT, DNS/DHCP/NTP server, file and print server, and handles other tasks like serving iTunes music and monitoring/controlling some hardware (for a while it was even a wireless AP, but that never worked well). My wife thinks it's my hobby (although she's perfectly happy to browse the web, print, and use it to look up scanned documents). I would never try to replace one of the 36-port EDR Mellanox boxes that we use at work with a FreeBSD machine.
