I don't see why cursor or their affiliates would be above the practice. It seems generally accepted that many discussions online devolve into, or were initiated as, marketing campaigns. It is probably particularly effective on software developers that claim to be blind to advertisements.
You said automated marketing. I mean I can get why you think I could be a shill for Cursor given my horrible sense of time. But for it to be automated is an interesting claim.
I definitely wouldn't be surprised if a small startup was engaging in their own posts, something I do find shameful. But that's quite a far shot from a wildly successful startup with 100M ARR engaging in some kind of scheme where accounts with active history are making automated comments. Just seems not only unnecessary but also unlikely given the risk and effort involved.
I think it's much more likely that out of the 300k users or whatever they have, a lot of them are on hackernews and have good things to say about the product and a 1.0 is a significant event.