"The Intel 82566 Gigabit Network Connection identifies out-of-band (OOB) network traffic (traffic targeted to Intel AMT) and routes it to the Intel ME instead of to the CPU. Intel AMT traffic is identified by dedicated IANA-registered port numbers. The [southbridge] holds the filter definitions that are applied to incoming and outgoing in-band network traffic (the message traffic to and from the CPU). These include both internally-defined filters and the application filters..."
100% of business PCs have Intel NICs because it's required for vPro. In the consumer market Intel NICs are generally considered (marginally) higher quality than Realtek. Intel Wi-Fi is also very common.
"The Intel 82566 Gigabit Network Connection identifies out-of-band (OOB) network traffic (traffic targeted to Intel AMT) and routes it to the Intel ME instead of to the CPU. Intel AMT traffic is identified by dedicated IANA-registered port numbers. The [southbridge] holds the filter definitions that are applied to incoming and outgoing in-band network traffic (the message traffic to and from the CPU). These include both internally-defined filters and the application filters..."