Low quality postings are often just there for compliance purposes to justify visas. Less ethical companies may casually mention to outside HR people that folks are applying.
It happens all of the time.
i've seen (and worked for) many startups that post reqs prominently to signal to the world (investors, customers, etc) that "things are going great" and "we're growing" while not even able to afford a req.
> never participated in interviewing a candidate where there is no intention to hire
I haven't seen as much of that, but have been in situations where the company is either doing great (transitioning during an acquisition) or not so great (running out of money) but you keep interviewing to "look normal" or to keep the pipeline just in case things get back to normal.