Most people who work at Big Tech companies don't wake up in the morning and think to themselves, "How do I wreck the Fediverse?"
Instead, they go, "I want to build something that I genuinely care about -- and I have the financial resources to do it!"
So they do because why not, right?
Where it gets dodgy is when the bean counters start asking, "How do we decrease churn?"
What I'm getting at here is that there doesn't need to be a grand conspiracy.
There just has to be nerds at Big Tech companies that want to build the "next big thing".
They have financial resources. They have marketing. They have a guy doing analytics who says, "This shift in our UI will increase revenue by a factor of 2X!"
Then you have the guy in accounting rejoice because it worked, and an executive who says, "Next big thing created shareholder value!"