I have some friends and family in Bali and I already ask them about this, and they reply to me "who's them and where they come from?"
FYI, for national security and the political reason at nowaday, Indonesian people must carefully before sending an invitation.
Thanks, I understand, if I can't find a reliable invite I will use one of these agencies like most people do.
That article is very helpful, and indeed most foreigners who live in Bali do it by constantly getting a new social visa every 6 months (via 1-2 days flight to Singapore), in fact that was the unanimous advice I got from the expat community there...