* Reviewers are basically forced to it for free. If you're a researcher you won't have the time to properly fact check a 40 page paper for free, it just isn't going to happen. So they (we) don't. The review process isn't very rigorous.
* Journals are leeching off of the public money by double whammying both the scientists and the institutes while providing minuscule value. Their gains are absolutely disproportionate to what they provide.
* Even the most involved and convoluted peer review processes aren't as anonymous as you think. When there's already a handful of people in your field, you can pretty easily tell someone's identity from their writing style.
I would love to pretend that the system is great and works very well but it just doesn't and this pretense and the phenomenon of holding new systems to a higher standard than the current one is preventing us from actually improving the system.