> Is anyone still writing assembly in the age of LLMs ...

Yes. Its "simplicity" is exactly why we pick and assemble piece by hand - we imagine the leanest way.

LLMs are (not just in Assembly, but especially) very precious as a natural language manual.

> an LLM can easily code it without errors

One day it will probably also be able to have sex, and yet we think we will not pass on the experience - unless, like some kind of coding, it will be a "strictly professional only for money" operation (like in Monty Python's Argument sketch).

Edit: as esteemed emptybits wrote above, rephrasing: it's /the Art of/ Assembly.