It depends on the job fair. My mid-tier university's career fair was as you describe. From talking to (women) classmates who attended Grace Hopper on the other hand it sounded very worth it. The lines were short (in the mid 2010s anyway) and many of the companies in attendance were scheduling next-day, single round interviews with job offers sent out by the end of the week. I have no idea if it's still like that but I can't say I'm surprised that, given how the tightly pool of entry-level jobs offering visa sponsorships has contracted, affected male students have gotten desperate and shameless enough to try it.