So - counter-example. I'm working with a UK organisation that currently still uses Twitter. I'm trying to persuade them to start their own Mastodon instance instead. Being able to reach Threads users, in addition to Masto uses would clearly be substantial selling point of setting up a Mastodon server - given the size of the Threads userbase - and much preferable to them starting a Threads account.
It would be right now, but the first step of Embrace Extend Extinguish is that: Embrace. Opening up to threads now might be extremely detrimental to the fediverse in the future, in the same way as happened with XMPP.
By this argument nothing should ever interoperate with anything else because clearly that's the first step toward destruction.
I'm writing this on Firefox, which interoperates with Chrome and Edge. Oh no! We need to get these browsers operating on incompatible protocols stat, before they all extend and extinguish each other.
In reality, "embrace extend extinguish" is not a law of nature. XMPP is not ActivityPub. They are separate things with separate circumstances. Did you know that XMPP is actually still functional and open and you can download clients and servers that use it to this day? The stories about how Google "destroyed" it have become wildly distorted folklore at this point.
Maybe on your instance - it's your loss. But admins have a choice - defed from them and lose access to all those users and having actual content worth looking at, or federate with them and actually grow your network into something that has enough going on to make people interested. As it is, I use Threads right now. I strongly prefer it to Mastodon. Kbin comes close, but has less content to idly scroll through. If no Fediverse site I use supports Threads, I'll keep on using it.
A bunch of people are pretty disgusting on the established fediverse as well. It's just that nobody has a way of imposing themselves in your feed.
And I don't use Lemmy, nor will I use Threads. I use services that broadcas information with both - that's different. I made a web site once, that doesn't make me a Google Chrome user. I send emails with Gmail users, but I still don't use Gmail. I just co-exist with people who do.
I'll take a smaller volume of stuff from people who want to engage over the quality of mass produced lowesr common denominator content that will come from Meta products.
The great thing about the Fediverse is that you can choose that even if Threads federates. You pick what you engage with, which communities and instances you subscribe to and which you block.
I want to stay as far away from Facebook as possible, my actual private data is safe because the login stuff doesn’t get federated and there isn’t much of it.
Why can't you do that? Use one of the many non-Threads servers to do it. Like Kbin, the one you're already using. Nothing about it changes if Threads federates.