True, the syntax is cryptic and unintuitive. Target is a subnet in CIDR notation, i.e. 192.168.1.0/24. The other various options describe the scan to perform. You can do simple pings, a full portscan, a quick portscan of the few most popular ports, and enable various IDS-evasion behaviors.
Fing provides something of a value-add by wrapping its sort of functionality in a nice UI. It's just amusing to see people discover Fing as though it were the first or only tool of its kind.
nmap is a universal stalwart of network security since the late 90s. It is the classic "hacking tool" long predating Metasploit, and Hollywood VFX people have even figured this out - it features in hacking scenes in Matrix Reloaded, Battle Royale, Bourne Ultimatum, and Elysium. I suspect ease of use has never been a priority, since its target audience is fellow open-source-savvy l33t haxxors.
