What you seem to be talking about are infringement suits where the judge throws out consideration of large numbers of patents and claims. That's about whittling down a problem of mind-boggling complexity to a group of questions that can be understood and answered in a reasonable amount of time. Those patents and claims aren't being struck down or ruled 'bogus'. They're just being ruled irrelevant to the meat of the case, to simplify the proceedings.

And most claims are thrown out of consideration simply because most patents only include a few independent claims. And as a practical matter if you can rule out infringement of an independent claim you've ruled out any possibility of infringement of its dependent claims.