Let's be clear about this: it's all bullshit. But people still want to be fooled by these scams, looking for the solution that brings in traffic with so less effort.
Why wouldn't this work?
Submitting to hundreds of searchengines? I only know a few that can deliver serious traffic, the rest is not important. Besides that: if you have some quality incoming links the searchengines will find your site by following them.
Within a few days or weeks on top ranks for whatever keyword you choose? If that was the case, what would all those SEO companies do all day?