I way over simplified it because I didn't want to write an entire book like you just did.

But yeah, you're right. In one of the recent books there are a couple of chapters where Guilliman was super pissed at The Emperor for not warning any of them about the Chaos Gods. Later on he realized why The Emperor did it that way. Humans who give the Chaos Gods any kind of direct attention only strengthens them, and then humans would wind up thinking about them during every waking moment. Guilliman finally understood that The Emperor was trying to save humanity from the terrors of its own mind, and that He and He alone would deal with the Chaos Gods when the time came.