I could imagine it might sometimes be the H1B thing, but more common are hyper-precise lists of technologies needed, when they already know the candidate they want but have a legal or administrative requirement to post the job.

Also, I get the impression hiring managers start with what they would like, and out of a long-bred instinct to have an opening bargaining position that's more than they actually want, they put down too many things.

Of course, if no offers come in, and they don't actually have an H1B or other candidate in mind, then maybe they go back and reduce what they're asking for, which would lead directly to this article's conclusion.