It seems long-form would be antithetical to their branding. Everything about their UI is meant to portray speed.
The first thing you see when opening the app is the quick logo screen, then the FYP automatically. Even when you swipe up, you can tell they use animation tricks to cater to my generation's ADHD proclivities.
I think these Social Media giants are going to learn a hard lesson about why they can't be a Wechat (at least in the US). We're not really into all-in-one platforms, especially when they're all really trying to offer the same exact features. But they realize that the Ad Monetization model for media is FUBAR and puts way too much power in the hands of faceless trillion-dollar marketing conglomerates instead of the owners of the platforms themselves, so they need different revenue streams.
It's ironic how the one Chinese company (TikTok) actually brands itself correctly to a US market and makes a killing, while the Domestic companies try to brand themselves to a demographic that barely exists or has their own dedicated platform they prefer.