By an insincere "how are you" they are extracting information on your current mood to engineer a proper communication protocol that is required to extract as much value for their personal objective as possible. I'm not disagreeing with you, just explaining their motivations to do it.
While it may be an intentional strategy for cold calling spammers, I doubt it because >99% of calls I receive do this, even from companies who I want to be calling me back, I think it's mostly a (pretty bad) cultural norm.
Also, for me it seems like a terrible strategy as I generally feel like responding to the greeting with: "Well, actually quite annoyed at this moment due to the appallingly poor way you've just started this call."
