Lets break this down
He sows jealousy between the Primarchs, anointing Horus as Warmaster and giving Fulgrim who is already to proud to see straight the honor of being the only one who can wear his sigil.
Who was he supposed to put in charge? All of them, can you say cluster fuck? Horus was clearly the best choice before the fall, no one could best him in combat, or strategy, or worlds conqured, and before he fell he did a better job then Guilliman remaking worlds.
The jealous Primarchs, well that was personal. Instead of being butt hurt that someone better then them was chosen, they should have refocused and strived to be better.
As for Fulgrim, I don't recall any of the Primarchs being jealous of this.
Then leaves the war without any word as to why. Of course they are going to be curious and it leaves them vulnerable to chaos.
Most didn't know about chaos, or didn't understand it from what I have read. Should they be curious, sure who wouldn't be. Does that mean the greatest humans ever need to have WTFHISSYFITS about it? I don't believe so, simply man up like some of the Primarchs did and carry on.
It's not about coddling them it's about not knowing what your fighting for when your realize your initial goal is unrealistic and then not being able to find out why.
It is about coddling, Horus, Lorgar, Magnus, Mortarion, all wen't into panic when he said all right greatest humans every yall take over daddys got shit to do. Instead of being like do your thing we got this, they went waaaaaahh waaaaaay daaaddddyyy!!!!!
How was the goal unrealistic? Had they not fallen to petty rivalries and jealousy who would have stopped them?
So the primarchs are lead by chaos to assume that the emp sent them on a wild goose chase while he becomes a god and will take glory for their conquest.
Only the whiny emo primarchs fell for this reason.
He wounds his most trusted son by competing a secret. He should have been up front with the primarchs in his intentions. It would have saved them the curiosity and magnus from destroying the chair.
Seriously, they were made to be perfect and needed to stop acting like children.
Yes I agree he should have, but he didn't. Lets wear our big boy pants and place them blame on the ones who deserve it.
I'm enjoying this!