WotC is probably willing to allow a lot of Larian's home brew if the dumbed down combat is projected to increase video game sales, even if they hate it as much as I do. They know DOS games sold well so probably Larian gets a lot of freedom. And whoever is taking the financial risk with the AAA budget is calling the shots there. We don't really know what their contract is like.
WotC also allowed Sword Coast Legends devs to completely transform 5e into a "video game" format with cooldowns and such. And it was a total disaster even with Dan Tudge, director or Dragon Age Origins, at the helm. The developer closed down after 22 years in the business. So games can fail. Just with D&D video games, the more they stray from the tabletop rules, the more they tend to suck. Hope WotC remember this lesson with BG3.
Wasn't Sword Coast Legends an action RPG? Dark Alliance is a D&D-based action game to come out this year, so I'd say despite the failure WotC will try again to get into this section of the gaming market. A failure of a single product to sell is not necessarily make a corporation change their strategy.
I doubt WotC is letting Larian do what they want simply as long it makes a game sell well. Even a big name such as BG3 would be considered in the context of their entire portfolio. And WotC' own business model is based on changing the "versions" of their products every few years.