Not sure that's true. One of the first adopters of D in production was Facebook, because one of the engineers (Andrei Alexandrescu) worked there and evangelised it heavily internally. Many projects were written in D. But eventually the cost of maintaining support for one more language in production didn't make sense. D didn't solve problems that C++ (another supported language at Facebook) didn't. The D code was rewritten. It's not that Big Tech didn't adopt it. It's that it didn't show enough value in time.
When you read about D and why it is not popular, one thing to keep in mind, is that there was D1 for a long time and then came D2 and this process was not as smooth as it could be. The dev progress was and stays slow but steady. D is in a better place today than it was 3 years ago for example.
What's your source on this?
I no longer have access, but if a Meta employee is reading this, I'm referring to a post that called Alexandrescu a "whirlwind of energy" in terms of how he personally encouraged and enabled teams to adopt D for projects.