I think they individually (and even collectively at a congregation level) sincerely believe what they are doing is right. Does that make it right? No. I think Amazing is correct about the marketing aspects of it, although I think they continue the practice out of respect for tradition --call it status quo if you like-- thinking that to ever change is admit error. That is very much a driving force in everything done at an organization level. At an individual level, I have no doubt of the genuineness of those going door to door.
-Joe
I don't want to be smart, I just want to be honest.