I use the Network -> LAN Devices page on my router, which is also my DHCP Server, to find MAC addresses and IP addresses of all devices in my home network.
Makes sense to me. Go to the device that dishes out the IP addresses to find out IP info in a network. With that device being the DHCP Server.
I prefer to keep my computers and network lean and mean. Less is more. So Fing can go finger itself, as far as I'm concerned.
Cisco business switches, like the nice 8 port jobbies you guys have been buying also come with commands for looking up info on connected devices, such as "Show Mac".