row type polymorphism vs TypeScript

I’m trying to understand what are capabilities of row type polymorphism. Most articles/posts I saw were written before even TypeScript came out. All things I saw so far, can be done with TypeScript, even as old as 2.2 (current is 3.5) and TypeScript correctly derives types even without annotations (hover a variable to see its derived type):

  • Change property
  • Add property

The only problem I see is that after a few such applications type declarations displayed to user become cumbersome.

Actual question: are there any more advanced examples of row polymorphism which TypeScript isn’t capable of?

PS: Please, use code-like notation, I’m having hard time reading this “fraction-like” notation.