> Why “stop linking to X”?
Clicking on almost any of the UI elements leads to a log in prompt, without showing anything else. For people without accounts (or those who don't want to make one), that's probably not functionally different from dropping a link to some forum that requires registration, albeit in this case I guess at least the main post is visible.
The Mastodon link in comparison has the discussion visible up front, which is nice to see! Now whether the fediverse is popular enough to actually have good discussions, that's a bit harder to say, but at least it's something!
I think Facebook also had similar issues, where it gates a lot of things behind a login prompt, quite user hostile, though also understandable why they'd do it that way.