If you want to make sense of Facebook's behavior and the incentives they're acting on, you have to keep in mind that they're not a social media company, they are not in the business of providing social media as a service to users, they are in the business of selling ad space. People of course don't usually like to look at just ads, so they need something to pair it with, which is where the need for "content" comes in. In the past, they've had the content come to them by providing infrastructure for posting content, but with the fediverse they see something even easier. The content is already there and they can just take it and throw their ads on it without the fear of getting sued like they would if they took directly from Twitter or TikTok.
In the past I think people have tried to excuse the existence of ads on the internet with the idea that it supports the service that you're using, that seeing ads is the price you pay for a free service. But that's not the case with the fediverse. Facebook looks to profit off infrastructure that is financially supported by individual instance admins, often out of their own pockets. They look to profit off users who don't receive any benefit from Facebook and haven't consented to being involved with them. Don't be surprised when people try to do what they can to avoid being part of their money making scheme.