I see your point, and I think that we both simply have different views on what is more important, and there's no need to convince eachother. For me, one of the main advantages of the Fediverse is that you're not directly feeding analytics and algorithms of a large company that is trying to monetize and manipulate you through content that you see - a company which business model is literally to change your behavior (which is a hyperbole, but still a quite from Social Dillema), and it's really important for me to not give them any chance to do that. And I don't see a scenario under which we would federate with Meta (or another multi-billion company) and this would not happen - and even if they wouldn't be able to directly affect what you see in your feed, your data and behavior will still help them train their models and AIs to be better at it, even if you didn't interact with the instance. I simply don't see anything of value federating with meta would provide, that would be worth this, along with the really probable risk that Meta is simply going for EEE, as mentioned in the other comments. And I think this was the main idea of Fediverse - to have a network of community-ran instances, where you are not the product, but the actors are indeed benevolent and selfless.

But I also understand your point of view, because you are right that defederating with them by default goes against some of the principles of decentralized ecosystems, and that there is a lot of content and userbase that we would be missing on. For me, I don't really mind if the growth of Fediverse is slower, but the community has similiar values as I hold, and I'd rather see it fail because it tried to uphold them, than see it turn into, or be destroyed by, Meta. Be it planned as part of EEE, or only a casualty. But then again, that's my point of view and so I vote to defederate, but It's good that there's someone like you with opposite side of view. I also don't think that either side is wrong, we just have different views about what the Fediverse should be.

And one last thing - I don't feel like the example with email is fair, because it's comparing a private messaging service between two users, and a social network where you provide content for other users, and none of the risks there are with Meta federating would apply. I've tried comming up with a better comparison, but couldn't come up with anything for quite some time, so I'll just leave it as is. Maybe someone else can think of something.