Which is why we should increase Imperial Authority(ask the emperor) and not interfere by ourselves in addition to putting down any [Large military conflicts] that occur so it'd downscale to duelling and backstabbery instead of open warfare.
Basically appeal to the martial nature and say "don't hide behind your men" or appeal to the love everybody has for Magnus and say "have faith in the emperor" and seek to establish judical procedures to tone down the amount of civil wars caused for stupid reasons.
Seriously, the only people who profit from nobility waging war on each other are mercenaries and vagrants, succession by conquest gives legitimacy to bandits. We want to (slowly) move away from that so we can focus on external threats. Better for the unity and stability of the realm that way.
Like those daemon worshipping arseholes.
Conflict will stay, but to use the capitalist metaphor, we'd be shifting from Laizzes-faire capitalism to welfare capitalism, much better for the commoners/workers.
The Four would make this impossible. Everything that happens in WHF happens because it amuses the Chaos Gods. If they stopped messing around the world could end at any moment. If the Empire looks like it is getting to stable and thus boring Chaos will make sure to reverse the trend.
We should play the cards we are dealt rather than chasing impossibilities.