Is this a problem? If so, can anything be done about it? The notion that formal training from a reputable institution should count for more than self-learned skills doesn't seem particularly problematic. And even the notion that credentials from highly regarded and highly selective institutions should count for more than those from less distinguished institutions also seems ok. Of course they do. How could they not?…
First, just taking an imaginary Silicon Valley company as an example, if qualified people who are more self motivated and better at learning than the average college grad are being passed over because of cargo-cult HR policies, that would be a clear economic loss.
Second, the supremacy of credentialling over accomplishment distorts the university education process itself. This includes rising tuitions (universities can charge more as alternative paths to middle class employment disappear) and lowering standards, as more and more people are pushed into and through the degree-granting process.
Finally, the predominance of "prestige" names in competitive positions is a symptom of decreasing social mobility and diversity.