I didn't claim there was IP infringement. IG & lots of other companies stole the stories format from Snap. Makes it easier for users who recognize the ui, but it's still got to be galling.
I remember both MySpace and Facebook status updates actually being a copy of Twitter style updates. I don't think Facebook even had status updates as we know it today when Twitter released.
Why? It's just a UI for something where there aren't many alternative ways to present it. Timeline, follower, following. That's it. The rest is styling and that is even less relevant.
I wasn't aware of any IP protection of Twitter's UI, which in one form or another has been done 100's of times.