Just to note, that as it is practiced in America, philanthropy is not a gift economy.
In America --
1. Funding is only provided in context of achieving some goal
2. Funding is distributed based on needs assessments
3. Funding must be spent within a time frame long enough to diminish the value of the funding over that time frame
4. Funding must not be distributed outside of approved channels
5. Those who receive funding are shunned by the community
6. The receiver of funding who reciprocates is debased
7. Funding is generally focused on individuals or households
Perhaps this is simply the institutionalized version of "Limited gifts in a commodity economy to encourage social bonds". Also note that the context here is specifically 'funding', or cash, not gifts of product or service. This may be viewed as the means by which capitalism "invests" into a gift economy.
In the context of volunteers assisting their church or social organization, the ideas of the gift economy do play out more as expected although the focus is typically on benefiting the organization and not (directly) its members.
(See
Gift Economy pt. 1.)