If by “configuring wifi by hand” you mean writing config files by hand, that’s actually not necessary with plain wpa_supplicant too. There is wpa-gui (or wpa-cute if you prefer Qt over GTK), which is basically a GUI frontend to wpa_supplicant, which makes adding new networks nearly as easy as with NetworkManager. But it’s a far less modern looking UI than the NM frontends.
If by “configuring wifi by hand” you mean writing config files by hand, that’s actually not necessary with plain wpa_supplicant too. There is
wpa-gui(orwpa-cuteif you prefer Qt over GTK), which is basically a GUI frontend to wpa_supplicant, which makes adding new networks nearly as easy as with NetworkManager. But it’s a far less modern looking UI than the NM frontends.