Comment by Kiro

I've implemented fluid mechanics using Claude (through Cursor) and it had no problem writing the logic and integrating it using my custom physics engine and custom renderer.

So no, I don't think your assessment is correct. LLMs shine when they get to implement something from scratch on a blank slate with clear API boundaries, whether it's a CRUD app or a physics simulation. Where I think they struggle the most is in big legacy codebases on tasks spanning multiple modules with lots of red herrings.