Khürt, The expectation is certainly not that the entire conversation moves to Twitter.
I’m doing this mostly to smooth the transition for the next generations of users who are still heavily reliant on Twitter and other social silos. In some sense, by seeing what is capable on my site, they may realize that it’s not quite as hard to own their own data and online conversations on their own sites. I’m doing it so that those who don’t have their own sites yet, can more easily be a part of the conversation. If they choose to participate via Twitter, why shouldn’t that be an option? I don’t feel like I need to dictate how others use the internet, but I can still enjoy using it and interacting on it in a way that feels far more natural to me. (As an example, I often notice that you use multiple modalities to interact with my site: sometimes you reply directly from yours with webmention; sometimes you use the native WordPress comment box; sometimes you use Twitter; and sometimes you use more than one of these! And honestly, why shouldn’t you be able to choose what’s most comfortable or expedient for you?)
Allowing a part of the conversation to originate from Twitter also allows the easier flow of ideas for those who are following them via that network. This isn’t much different than if everyone were actually using their own website to carry on the conversation, it’s only the mechanism that has changed slightly. They could also manually log in on my site to leave a reply almost as easily, but perhaps they don’t want to take the extra steps? Perhaps they don’t want to give out their email address? Or perhaps they want that added network effect that Twitter allows them?
For the most part I’m trying to lower the barrier to participate in the conversation, and doing so wasn’t very difficult on my part.
While their small portion of the conversation may live on Twitter (this is probably better semantically than saying it “moved to Twitter”), through backfeed via webmention, all of the conversation is still staying on my own website. There’s a mirrored copy of it in both places to some extent. I suspect that many will see the limiting nature of Twitter and that they’re potentially missing out on flexibility as well as the rest of the conversation that does live on my own site. As a case in point, I’m posting this reply into the thread and syndicating the reply to Twitter where I know you’ll see it within the same thread you started. The conversational loop has closed for you within Twitter while also being closed on my site at the same time. The bigger difference is that I’m not limited by characters on my own site.
Perhaps one day all sites will support webmention organically, and all of this becomes moot, but in the erstwhile doing this effectively lowers the barrier for those who don’t have their own sites while still allowing me to participate the way I want.