My understanding is that the patent office checks if the patent is substantially similar to previous patents. A non-novel idea can easily get through if it is phrased in a different way or never appeared in an earlier patent.
I do not feel this is a problem. A patent just provides a legal presumption that you are allowed to file a lawsuit. Some people argue that this enables patent trolls, but patent trolls exist because con artists will always try to ride on the coattails of success. My view is that low standards for patentability provides protection against patent trolls: a company can patent early and often in the years before they hit it big and start attracting con men. Easy patentability also deepens the pool of well-documented prior art, providing more clubs with which to beat up patent trolls.
Filing patents isn't exactly free either, in terms of time or money.
Also, how exactly do you "beat up" patent trolls? They threaten to sue you, and you . . . threaten to spend millions of dollars on court fees to have their patent invalidated? That doesn't work so well unless you have millions of dollars you don't happen to need.
Are you really suggesting that all those small-time devs sued by lodsys over BS patents would have some recourse if only they'd filed a bunch of patents themselves? Or if only their predecessors had somehow flooded the patent office with enough BS patents that the lodsys ones got thrown out as prior art?
The whole "patent everything, let the courts sort it out" philosophy sounds nice in theory, but the whole problem is that it's freakishly expensive to sort those issues out in court, so patent lawsuits end up as shakedowns: you either pay up in licensing, or you pay up in laywer fees. Either way you're paying someone.
I do not feel this is a problem. A patent just provides a legal presumption that you are allowed to file a lawsuit. Some people argue that this enables patent trolls, but patent trolls exist because con artists will always try to ride on the coattails of success. My view is that low standards for patentability provides protection against patent trolls: a company can patent early and often in the years before they hit it big and start attracting con men. Easy patentability also deepens the pool of well-documented prior art, providing more clubs with which to beat up patent trolls.