You're absolutely right!

These points might be fake, but they are far from being useless, and actually have monetary value.

There is a market for buying and selling "aged" Hacker News accounts (3 USD <-> 15 USD for ~500 points) and upvotes / downvotes

By purchasing just ~300 karma points, founders can unlock an uplift of tens of thousands of dollars in visibility on the home page (clients and investors).

So the LLM comments are not here just for fun, they are clearly farming points.

Ironically, it also increases actual human engagement. This way the day Ycombinator wants to announce something, they already have more public than if there was low engagement.

Like the shilling you mentioned, these bots can push downvotes and flag competitors service.

Essentially the same as on Reddit. If you have incentive, you have a market.