If one alliance leads and nobody follows, that alliance becomes a very easy target.
The treaty web is basically all about mutually assured destruction. If you don't play the game, you make yourself and your allies vulnerable without connections. If you do, you are just allowing yourself to be used by others for this kind of thing.
The treaty web is a serious problem, but you can't have one alliance "set the example[,]" you need many alliances to act together to really change it. But there's too much inertia to do that.