Until we all buy from robots, and maybe we're not far off, but until that day comes - marketing/sales remains an inherently human activity.
It's a cliché and a truism, but...
People buy from people.
And people are driven entirely by their psychological makeup, by their: cognitive processing, modulating of emotion, rationalisation, coping mechanisms, values, motivations, framing.
How/what we think (cognition), triggers how we feel (emotion),
triggers how we buy (behaviour).