Paper based advertising and con artists always existed, but the availability of email over the Internet made automation possible and opened up the possibility to do that on a totally new scale with spam and phishing. The example in the post (impersonating an old mother) is a kind of phishing that doesn't scale if criminals have to do it by themselves. An AI able to handle the conversation would make it possible to make much more money in a single day. By the way, that would be detrimental to the less technological criminals because there is a limit to the number of such a calls you can believe. Probably either 0 or 1. A "90% of the market vs all the others" rule for criminals as well?

What will it be like when it's AI all the way down?

Seriously though, the level of evil that can be perpetrated as technology evolves is scary and I ask myself sometimes whether humanity's wisdom will manage to catch up to it's intelligence before it destroys itself in very creative ways... Though I must admit that criminal AI feels much less threatening to me than criminal biotechnology.