The EPC is like any other HAM radio organization, a group of HAMs who are interested in promoting PSK mode(s). In order to keep interest up on the PSK mode(s), the idea of collecting "EPC Numbers" has been developing.
Personally, each member enjoys the camaraderie of kindred spirits, whether the activity is informal rag chewing or numbers chasing or a more formal EU PSK DX Contest or QSO Party.