> I also probably would not have responded favorably to that wording – irrespective of if they were correct.
Why not? I see nothing wrong with this sort of feedback. It's blunt, but constructive.
It does seem vague though. It’s almost akin to saying “I could’ve done this in half the code”. Well add your PR then.
They did, they implemented a crazy fast terminal renderer (that still supports advanced features like right-to-left languages in Unicode, etc.) from scratch in about 3,000 lines of code just to prove their point: