Yeah, it also coincided with the fall of Congolese music in the diaspora from 2002/03. Artists not being able to fill Zenith's and sometimes even halls like LSC & La Madeleine, the ngulu-affaire messing everything up, bands having difficulties for getting visa's, tour-promoters only wanting a list of max. 15 people, long tours not having huge impacts anymore, artists just spending 2 months in Europe and returning back, etc.
If you look well the three Bercy's of Werrason, JB Mpiana and Papa Wemba were all done in a rush. Koffi Olomide and his management really took the time to organise the event well, looking for donors, the stage, guests. Just look the difference of the stage Koffi had and that of JB, Wemba and Werra. They all performed there just because Koffi did and the pressure from their fans and staff. There wasn't any demand from big concert-promoters to let them perform at Bercy. Werrason had the chance to perform at Bercy, because of concert-promoter Yann who normally wanted to have him at Forest National in Brussels, but Werra's staff insisting on letting him perform at Bercy, which he did. JB Mpiana also did it with the pressure from his staff and fans after being mocked by the WMM-camp of having skipping Bercy (ba sauter Bercy). The same for Papa Wemba.
Also those 4 Bercy's weren't well promoted how it has normally to be. Despite having huge mpiaka's, the stars Youssou N'dour and Alpha Blondy benefited from good promotion of the French press, television and newpapers. While JB Mpiana and Werrason had zero promotion, just the fanclubs and the staff doing everything to mobilize the whole Congolese diaspora in Europe. Koffi Olomide only appeared after the show on the French television (TF1, France2, etc.) because he was the first African artist to perform there. But before the show no one French television-channel promoted his event. Papa Wemba appeared after the show on tv because he already had a big notoriety in France, due to his worldmusic-career. But like Koffi no French television promoted his event.