Yup, Instagram still works.
Large companies, particularly in the EU, are not allowed to throw their weight around to privilege their own services and apps.
Google prioritizing their offerings over other vendors on a search they control is far different than "Can't post on Facebook from Twitter".
Google has put itself forward as a fairly agnostic search. No one signs up to be indexed by Google. It works more like a common good. So when Google starts offering a service, then puts its own offerings before others in its search. That's dirty pool.
But that's not what's happening here. Facebook is a platform to connect with other people who are also on Facebook. It doesn't purport to be a central hub for anything but Facebook. It's just not allowing Twitter (and others) to post on users' behalf.
The argument here is that Facebook is a natural monopoly and by only allowing Instagram to post automatically to a users timeline, they are leveraging that legal natural monopolies power to advantage Instagram.
Microsoft had a monopoly on the retail operating system space and leveraged that monopoly to force vendors into bad positions that excluded other operating systems a shot on a fair market. They also used their position to push their products to the detriment of other competitors.
As far as I can tell, Facebook just has a monopoly on Facebook. Which is to be expected since Facebook is Facebook.
I asked how would this trigger anti-trust proceedings because Facebook is not abusing a monopoly position, they're just not letting other services post to their site.
You responded by basically saying "Yeah, but people think they are". Which really doesn't address anything. So I asked more directly what do they have a monopoly on.
I know people think they're a monopoly. I think those people are wrong. At least until they can tell me a monopoly on what.
I thought Facebook was on the stock market...