It's hard to address anything because you're not open to consider that damage isn't the only metric, and bring up silly arguments like 1vs1 which has literally no place in a team game. GNB has no crowd control beyond its LB to secure kills, GNB will be out of dashes if it tries to chase too long, GNB can be baited to overextend if it really goes full baboon and punished by a team that actually knows how to take advantage of this. If you're fixated on the scoreboards at the end of games, where damage tallies only tell a partial story btw, then you'll also have noticed that GNB damage numbers are padded like crazy at times because people keep hitting the GNB under nebula like monkeys, so guess what happens at the end?

If damage is such a huge factor, and don't get me wrong, damage is important, then why is that green/blue (no GNB) comps perform better than full red ones? Or than a full red one with a GNB?

GNB is a very good job though, sure. Not arguing against this. Perhaps I got baited by the 1vs1 argument...