Perhaps somewhat counterintuitively, this current paradigm treats dialog as a static supervised learning problem, rather than as the interactive agent learning problem that it naturally is.
a typical pipeline is to collect a large dataset of human-human dialog (Lowe et al., 2015;Das et al., 2017a;de Vries et al., 2017;Mostafazadeh et al., 2017), inject a machine in the middle of a dialog from the dataset, and supervise it to mimic the human response.