This is an interesting take on the matter, and you do have pretty good points. For me personally, I don't think that bringing in the Meta crowd would bring us much value, as I've already stated in the other comment. I'm not interested in the style of content both Facebook and Instagram provides, and I don't really like the userbase - but that's also only my personal view, and it's not something that would warrant defederation.
I'm worried that due to sheer amount of people they have, it would simply drown any content from other instances and would make it harder to find (and also really hard to moderate - Meta has significant resources to moderate that many millions of users, something smaller instances can never reach). Hot and Top would simply be filled by influencers, and it would take significant effort to just unsubscribe or block all of them (I'm actually not sure here how does the frontpage works, if you select all instances - is it like All on Reddit, or like frontpage with a set of default communities, but not everything shows there?), while also making it pretty hard to find smaller communities with different crowd - which is what I like on Lemmy as of the current state.
As soon as someone with actual resources wants to contribute, we shut them out? Folks, if a single organization could bring down the fediverse, then the “decentralize so that no one can gain too much power” model is proven wrong, and it was bound to fail anyway.
I don't really agree with this. It's only my own take on things, but I don't believe in the slightest that Meta wants to contribute to the Fediverse or has any of it's interests in mind. Nothing good will come out of it, Meta will only exploit the Fediverse for free content they don't have to host or pay for to kickstart their own platform, and then slowly bring users over there with QoL they have resources to implement for their instance. I'm not worried that they will bring down the Fediverse - that's where the decentralization will work as it should since other instances can defederate as soon as a problem appears, and keep their content and their userbase. What I think is an issue is that unless we defederate soon enough, Meta will exploit Fediverse for their gain only, slowly make people used to the QoL they are providing and have resources for, and when it finally gets bad enough that instances decide to start defederating from them, it will be too late, and Fediverse will loose users and content creators, because they were used to and interacting with communities on Meta's instance - which were the best choice simply due to a high number of users coming from Meta's userbase. Which brings me to
That’s what defederation would imply: people who want to interact with Meta’s folks and be in touch with Meta’s community would end up creating accounts there. We’d be handing users to Meta by doing that.
This would be even worse if we defederate later, once it turns out that Meta is trying to do something that really warants a defederation. As I've said in the previous paragraph - Meta's communities will be larger and have more content, and more people will leave once we defederate because they are used to those communities, including people that would not leave there now.
And the last issue is the fact that it serves so much data about users and their interactions right into Meta's algorithms, without them having to make any effort for it. And I really don't like that, and it's the reason why I'm avoiding anything Meta even touches. But then again - that's my personal issue.
To sum it up - some commenters said that it's a risk that we should try and take to see how it will go - I'd personally rather not risk it, and just keep Meta or any other multi-billion corporations out of this ecosystem. You can be sure that they don't have anyone's best interest in heart, and will only exploit it for monetary gain. And they have teams of experts in the field already working on strategies about how to exploit us as much as possible. I say don't give them a chance, this is something we cannot win and it will only make everything worse.