It would be interesting to add another axis to that diagram about direct impact on work output, which you would expect to be highest at the structured level but might in fact be most noticeable at the PLN level.

In my opinion, at least, making a sincere effort to engage your employees has a higher impact on productivity than other faux morale building activities. Empowering them to create a meaningful PLN is a good first step towards supporting their own personal goals.