Regrettably, limiting alliance sizes wouldn't actually limit coalition sizes, so there's no way to do that.
In that case, reparations would make it so that nobody would war at all, since losing would be ridiculously bad. That or it would cause perma-wars where no-one would ever stop turretting, since once they did they'd pay for the damages they inflicted, which disincentivizes peace rather than encouraging it.
Offensive turretting isn't boring at all, either: dogpiling is what's boring.