There`s no honor among thieves, mobsters are the same kind of low life as the gang members. Also some "street gang" cells are relatively organized and should be categorized into the realm of OC, and LCN seems to only do business with those who are organized, average street gangs are still no value trash though.
Also LCN has been doing business with the Ndrangheta in NY for a long time, I remember one of the Genovese associates was killed in 2015 because of snitching on the Calarbians.