Yes you are right, in order to make an ALV editable, we need to use the method
lo_value->if_salv_wd_table_settings~set_read_only( value = abap_false ).Its for the entire table.
Now its up to you how you customize your ALV by using set_read_only_fieldname. Its basically for cell based operation, but in your case we are using it for the entire row.
Hope it clears you doubt.
Award points if helpful.