You should check out the lawsuit that the Dragonlance creators have filed against WotC/Hasbro to see just how wrong you are about their creative control.
Interesting, just went and read about it. Sad to see, but I don't see the connection to creative control. WotC didn't move forward with a book contract they signed for some undisclosed reason, and the authors countersued for breach of contract. The rest looks like regular lawyer stuff.
If Larian was having to get every adjustment to the balance of this game pre-approved by WotC, then it would be impractical to even make the game. It would be such a slow and cumbersome process that you couldn't make a game under those conditions. Especially when you realize the tiny tiny team behind 5e.
