I think you're right about the Fakebook possibly subverting Fedi, email has been subverted a long time ago, and I even wrote about it quite a while ago: https://social.076.moe/url/78493 or http://ryocafe.i2p/blog/liberate-email-ignore-dkim/

On the other hand, unlike email, everyone is spread over many instances, and setting up your own isn't all that hard.
So if Fakebook really wanted to centralize it into their own hands, they'd probably need to get 80% or more of the world population using their instance, then cut everyone else off (like how Gab, """truth""" Soycial, and GC2 did), and make setting up your own instance as undoable as possible (or just make it seem like so).
And so far, Gargeon did a good job resisting the corporate takeover, so that's good to see.

Also, Fediblock has done more to destroy ActivityPub than Fakebook could possibly have done.
Because Fediblock is by design a seggregation tool to exclude all the instances that only slightly disagree with the status quo (ironically the side that claims to be against the ruling ideology abide to exactly that ruling ideology, and it's those of us who don't who are being called ismphobia all the time).