I used to work for a Big Eight (now Big Six) Accounting firm. In addition to a tremendous amount of pro bono work that we did, the firm required all of its staff accountants, managers, and partners to become involved with one of the many not-for-profit organizations in the Cincinnati area.
The rationale was that each employee had an obligation to the greater community, to give something of himself or herself to others. And while I also heard that the "real" purpose of this requirement was "practice development" (translate marketing), there were certainly more likely places to network for "paying" clients. And we were in those places, too.
Barr, Terri Feldman, "Service learning: What is it? Can we use it?" (1997). Service Learning, General. 9.