Also, I think you have a very glorified idea of peer review.[...]
Not all journals have the same high standards. That's why a paper published in a lesser journal is usually given lesser weight. If a paper makes big claims and is submitted to a prestigious journal, it's expected to be scrutinized very carefully. In fact, some journals from national academies go so far as to require sponsorship from a scientist with high stature before the paper is accepted. It is assumed that the scientist has read the paper, and will be extremely embarrassed to have his name associated with the paper if it turns out to be wrong.