The problem is that if you don't have any screening, then you get a flood of candidates, and it takes someone's full time job to sift through them. HR needs to be well trained on what to look for, but they are often a necessary gatekeeper in my experience on the hiring side. The goal is to keep the number of qualified candidates who get filtered out at a reasonable level.
(I completely get that this is unfair. If you went to MIT and have a high GPA, you are gonna make it past the gate more often. Community college, but an excellent coder? Unfortunately you will be rejected more often by HR. It's completely unfair, but companies can't reasonably interview every candidate who submits a resume.)
