Typical arrogance of people used to being the smartest person in the room and thus think they can out-smart Zuck. But Zuck doesn't need to out-smart anyone, he can just out-spend them easily.
Well... They are of course right about the fact that these sorts of decentralized systems don't have a lot of privacy. It's necessary to make most everything available to most everyone to be able to keep the system synchronized.
So stuff like Meta being able to profile you based on statistical demographic analysis basically can't be stopped.
It seems to me, the dangers are more like...
Meta will do the usual rage baiting on its own servers, which means that their upvotes will reflect that, and those posts will be pushed to federated instances. This will almost certainly pollute the system with tons of stupid bullshit, and will basically necessitate defederating.
It'll bring in a ton of, pardon the word, normies. Facebook became unsavory when your racist uncle started posting terrible memes, and his memes will be pushed to your Mastodon feed. This will basically necessitate defederating.
Your posts will be pushed to Meta servers, which means your racist uncle will start commenting on them. This will basically necessitate defederating.
Then yes there's EEE danger. Hopefully the Mastodon developers will resist that. On the plus side, if Meta does try to invade Lemmy, I'm pretty confident the Lemmy developers won't give them the time of day.
If rage bait happens, because of Meta, then rage bait can already happen, because Mastodon cannot be bothered to implement custom algorithms for now and yet it is required, because a linear timeline is easiest to exploit with scheduled tweets picked from secondary accounts proven to be baity.
I'm not a Mastodon expert, but I'm pretty sure you can still get their memes if they reply to you (or @ you), or if they post to a tag you're following.
Then yes there’s EEE danger. Hopefully the Mastodon developers will resist that.
Unfortunately developers can do very little to prevent that.
EEE works by first attracting a large userbase into a service and later on prevent them from leaving.
It's up to instances admins and users to defederate to prevent EEE.
If some random dude comes in and opens a new instance, and then it comes out that this dude willingly associates with white supremacists, is a known creep, and even had a hand in an actual real life genocide, everybody would defederate without a second thought.
But suddenly that dude is Facebook and has a shit ton of money and everybody is just wait and see.