I first noticed these kinds of "hidden" hiring messages almost 10 years ago. I thought it was cool for like 20 seconds until I realised that it is no different than just applying normally on their normal hiring page.
So the fact that more people find out about this, is like people discovering that a hiring page exists on companies websites. Which they already knew.
What I'm actually annoyed by is that companies are still doing this stupid thing.
It's not like the sites are offering you a job, they're saying you should interview with them. I have not heard of anyone getting hired because of this.
I don't know about annoyed, but I wouldn't want to talk about any movies I haven't seen with the author, or involve them in planning a surprise party.