As an associate editor and frequent reviewer, I can say with confidence that peer review filters out at least 90% of the garbage that journals receive as submissions. It also provides useful feedback to researchers who cannot otherwise get it. People submit papers knowing they will get rejected because they want to read the referee reports.
In my field, academics simply do not trust a result until it has been replicated and scrutinized by other researchers. If that doesn't happen, it's usually because the result was not interesting enough for anyone to care. If the scrutiny reveals problems, that undermines the credibility of the authors, which is ultimately more important than whether they get the pub.
A final comment: Peer-reviewed journals differ dramatically in their quality. If you don't know what the good journals are, you should expect that your reading will include a bunch of crap that no serious person in the field would pay attention to. Why these crap journals even exist is a mystery to me.