Moving away from chronological allows them to feed you more addicting content, as does the infinite feed. They involved together because they work together synergistically.

It’s of no value to point out both can technically be implemented independently. That isn’t what happened, and even if it did it would still be user hostile.

I still don't understand. If TikTok simply showed the user every single TikTok ever created, strictly in reverse chronological order, it would still be an infinite scrolling UI.

The sorting algorithm that they choose isn't what makes a UI infinite scrolling or not, they're completely orthogonal. In MVC architecture terms they're model and view respectively...