I doubt WotC has too much influence on Larian now although it would depend on the actual contract.
They definitely have influence. It is a billionaire company, they pay the best lawyers to write such contracts, and since they have the bargaining power, it makes sense that they write the contracts in their favor.
I also doubt that WotC has a problem with Larian bending the rules. They are on a big D&D marketing offensive with games and the upcoming movie, so likely care more about a flashy presentation and name dropping than staying true to their rules.
I still think its illogical to not enforce the rules, given that doing so could lead to cross-sales and sell more books, which would in turn create more D&D fans that would consume other D&D products.
The game can be flashy and cinematic AND follow the rules. Gamers will play regardless, the D&D crowd will be turned down though, and the books are more popular than ever.
