Junior programmers may not (even probably don't) have a good idea of what questions to even ask. Younger juniors (e.g. right out of college) may even feel intimated or anxious that their question is "stupid". This isn't helped by the software industry's reputation (well deserved, in my opinion) of being populated by arrogant people with little or no tact or empathy.

Reliance on online resources is, in my view not a substitute for experienced mentorship: there is the paradox of choice, and the plethora that creates this paradox is of generally poor quality. Except for textbook or trivial problems, moreover, much of the resource material online is too generic or only marginally applicable to the depth and breadth of technology issues that face a real business and its needs.