Responding just to the title and opening sentences, I'd say that "on-demand learning" is clearly better for experienced tech workers and less good for newcomers

Responding just to the title and opening sentences, I'd say that "on-demand learning" is clearly better for experienced tech workers and less good for newcomers (though it can forge them into experienced workers). A very experienced tech worker should be able to quickly learn new things as needed without conceptual cognitive overload when the new thing fits in reasonably well with their past experience. For newcomers, a stressful on-demand learning exercise can create the skills needed to manage the conceptual cognitive load in the future.