I just read this point in a comment and wanted to bring it to the spotlight.
Meta has practically unlimited resources. They will make access to the fediverse fast with their top tier servers.
As per my understanding this will make small instances less desirable to the common user. And the effects will be:
Meta can and will unethically defedrate from instances which are a theat to them. Which the majority of the population won't care about, again making the small instances obsolete.
When majority of the content is on the Meta servers they can and will provide fast access to it and unethically slow down access to the content from outside instances. This will be noticeable but cannot be proved, and in the end the common users just won't care. They will use Threads because its faster.
This is just what i could think of, there are many more ways to be evil. Meta has the best engineers in the world who will figure out more discrete and impactful ways to harm the small instances.
Privacy:
I know they can scrape data from the fediverse right now. That's not a problem. The problem comes when they launch their own Android / iOS app and collect data about my search and what kind of Camel milk I like.
My thoughts:
I think building our own userbase is better than federating with an evil corp. with unlimited resources and talent which they will use to destroy the federation just to get a few users.
I hope this post reaches the instance admins. The Cons outweigh the Pros in this case.
We couldn't get the people to use Signal. This is our chance to make a change.
The instances defederating Meta will shrink and collapse into their own seperate Defediverse. The debate shows the risk of so many hobbyist instances and admins powertripping their view who the users are allowed to talk to, that a corporation is perhaps more reliable. It hurts the users, hampers communication channels and people will flock more to the Mainfediverse further accelerating more power to fewer instances.
If you were looking for a network seperated from the outside general world, you perhaps should have joined a closed instance, network and forum. It goes against all what the Fediverse tries to be, a multi-purpose communication tool across communities, corporations and cultures with the possibility to create seperated and shielded communities.
The current fediverse is like a small mall or downtown with local shops and unique things to do. Meta is like Walmart coming in and overwhelming the existing businesses and running them out of business through unethical practices.
It isn't like people won't be allowed in the fediverse if they also use threads. The desire is to avoid threads using the fediverse to drive everything's else out.
The fediblockers are only driving themselves out. Your analogy is wrong, they cannot run Mastodon out of business. Should Meta decide to be feature incompatible and itself defederating a significant portion will leave. The fediverse itself is so alive, because of the rotten smell of Twitter, reddit and Facebook. Meta will fail with Threads, if they try to extinguish others.
nobody is trying to run anything out of business, that'd be foolish. The goal is preventing them from ruining every other community once they inevitably gain control of it all